Sourdough Chocolate Cake Recipe (Discard/Active Starter)
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If you’re a chocolate lover through and through, this Sourdough Chocolate Cake is everything you want—super moist, light, deeply rich, and surprisingly easy to make from scratch. The espresso powder deepens the chocolate flavor, the hot water helps bloom the cocoa, and the sourdough discard adds incredible flavor while keeping the crumb soft and tender.
And don’t even get me started on the dreamy chocolate buttercream—it’s the kind of frosting you’ll want to eat straight from the bowl. And if you love baking cakes with sourdough discard, my Sourdough Guinness Chocolate Cake and this Sourdough Vanilla Cake are two more recipes worth making next.
Quick Look: Sourdough Chocolate Cake
- Prep Time:
- Fermentation Time:
- Bake Time: 22–27 minutes
- Total Time:
- Servings: Two 9-inch layer cake
- Calories: ~
- Cook Method: Baked
- Flavor Profile: Rich, moist, and deeply chocolatey with a subtle tang from sourdough discard. Topped with a creamy chocolate buttercream frosting for an indulgent, celebration-worthy cake.
- Difficulty: Easy — Simple ingredients, no complicated techniques, and comes together quickly for any occasion!
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Why You’ll Love This Sourdough Chocolate Cake Recipe
- So moist it stays fresh for days—The combination of sour cream and sourdough discard keeps this cake incredibly moist, not just on the day you bake it but for days after, making it a great cake to prep ahead for a dinner party or celebration. These Sourdough Brownies are made with sourdough discard, too, and are just as impossibly moist.
- Bake it your way—This cake works as a two-layer cake, a 9×13 sheet cake, or cupcakes, so you can bake it however your occasion calls for. And if you love the idea of a chocolate sourdough cupcake, these Sourdough Chocolate Espresso Cupcakes take it to a whole other level.
- Simple and quick—Despite how impressive this cake looks, it comes together with simple ingredients and no complicated techniques, making it just as easy to pull off on a weeknight as it is for a special occasion. If you love simple sourdough baking, this Sourdough Vanilla Cake is another one that delivers every time.
- You can long-ferment it—If you’re not ready to bake this chocolate cake right away, no problem. This cake can be long-fermented overnight in the fridge. For another celebration-worthy sourdough cake, this Sourdough Red Velvet Cake is well worth the bake.
Ingredients & Substitutions
* To find precise measurements, scroll to the bottom of this post to find the recipe card*
- Flour—I used sifted all-purpose flour, but unbleached cake flour works well in this recipe too. If you’re not using a kitchen scale, be sure to fluff the flour first and then spoon it into your measuring cup for the most accurate measurement.
- Cocoa Powder—This recipe calls for unsweetened natural cocoa powder, not Dutch-processed cocoa powder. Natural cocoa powder, along with the sour cream, reacts with the baking soda to give this cake its rise, so swapping it out for Dutch-processed cocoa powder may affect the texture and cake rise.
- Baking Soda — Make sure your baking soda is fresh and active before you start. If it’s expired or has been sitting open for a while, the cake won’t rise the way it should.
- Sugar—I used a combination of white/granulated sugar and light brown sugar, but you can swap it out for coconut sugar.
- Sour Cream — The sour cream makes this cake so incredibly moist. If you don’t have any, Greek yogurt works as a substitute.
- Espresso Powder (Optional) — I highly recommend adding espresso powder to this recipe. It doesn’t make the cake taste like coffee, but it really brings out that rich chocolate flavor.
- Oil — Any neutral oil will do. I always reach for avocado oil, but feel free to use whatever you have on hand.
- Sourdough Discard—For sweeter recipes like this one, I prefer using fresh sourdough starter discard no older than 1 to 2 days. You can also use an active sourdough starter; make sure to use the same amount in grams.
- Hot water- I used wated that was 110 degrees F. This not only mae the batter nice and smooth but it also helps “bloom” the cocoa powder, which give this cake its extra rich chocolatey flavor. For an even richer flavor, swap the hot water for strong hot coffee!
Chocolate Buttercream Frosting
- Unsalted Butter — Make sure your butter is fully softened before you start. Softened butter gives the frosting that creamy, smooth texture.
- Cocoa Powder — Unlike the cake batter, either unsweetened natural or Dutch cocoa powder works for the frosting.
- Powdered Sugar—Add the powdered sugar one cup at a time while mixing. You don’t want to dump it all in at once, or you’ll have sugar flying everywhere.
How to Make the Best Sourdough Discard Chocolate Cake
- Preheat your oven to 350°F and line two 9-inch cake pans with butter and parchment paper.
- In a medium mixing bowl, sift together the flour, natural cocoa powder, baking soda, espresso powder, and salt. Cocoa powder is notorious for clumping, so don’t skip the sifting. Add the sugars and whisk until combined.
- In a separate bowl, whisk together the room-temperature sour cream, eggs, oil, vanilla extract, and sourdough discard or active starter until smooth.
- Pour the wet ingredients into the dry ingredients and mix with a rubber spatula until there are no more streaks of flour. The batter will look very thick at this point, almost like brownie batter.
- Pour in the hot water and whisk until combined.
- Divide the batter evenly between the two prepared cake pans.
- Bake for 22 to 27 minutes or until a toothpick inserted in the center of the cake comes out mostly clean with just a few moist crumbs.
- Remove the cakes from the oven and place them on a wire rack to cool completely.
Make the Chocolate Buttercream Frosting
- In a stand mixer with a whisk attachment, beat the softened butter on medium speed for 2 minutes until light and fluffy.
- Add the powdered sugar one cup at a time on medium speed.
- Add the cocoa powder, heavy cream, vanilla, and a pinch of salt. Mix on low, then beat on high until light and fluffy.
Decorate
- Before decorating, make sure both cakes are completely cooled. Even if they feel slightly warm, the frosting will melt into a sugary mess
- If the cakes are domed, slice off a thin piece of the top of the cake with a serrated knife to help level the cakes. This helps the cake to lay evenly when layered.
- Place the bottom layer on your cake stand, top with about a cup of frosting, and spread evenly with an offset spatula or flat knife until it’s evenly covered.
- Place the second cake layer on top, cover evenly with another cup of frosting, then cover the edges with the remaining frosting.
- Leave the cake uncovered for at least 30 minutes before slicing for cleaner, neater cuts.
I kept my cake simple and went with just the frosting, but here are some decoration ideas if you want to take it a step further:
- Chocolate ganache
- Fresh fruit like berries
- Chocolate shavings or chips
- Chocolate or gold sprinkles
- Macaroons
McKenna’s Helpful Tips
- Use room temperature ingredients. Make sure your eggs, sour cream, and sourdough discard are all at room temperature before you start mixing. This helps everything come together smoothly and gives you a more even, tender crumb.
- Don’t overmix the chocolate cake batter. Once you combine the wet and dry ingredients, mix until you don’t see any more streaks of flour and stop right there. Overmixing will make your cake dense instead of what you want: soft and tender.
- Don’t panic if the center sinks a little. Unlike flour, cocoa powder doesn’t have gluten, so it can’t hold the same structure. A slight sink in the middle is completely normal for a chocolate cake even when it’s fully baked through.
- Try it in different pan sizes. You can also bake this in a 9×13 pan or turn it into sourdough cupcakes. See the notes below for instructions.
How to Store
This sourdough cake stores really well. Give the frosting at least 30 minutes to set before covering it up. It’ll keep just fine at room temperature under a cake dome for up to two days. If you need it to last longer, stick it in the fridge in an airtight container, and it’ll be good for up to five days. Take it out about 30 minutes before you serve it because cold buttercream straight from the fridge is dense and loses that light, creamy texture. To freeze, put the frosted cake in the freezer uncovered for about an hour first to firm up the frosting, then wrap individual slices tightly in plastic wrap, followed by a layer of foil, and freeze for up to 3 months.
Sourdough Chocolate Cake FAQs
Do I have to use espresso powder for this sourdough chocolate cake?
The espresso powder is optional, but I highly encourage adding it! It won’t make your cake taste like coffee at all. It just really brings out that rich chocolate flavor in a way that’s hard to explain until you taste it.
Can I use a different frosting for this homemade sourdough chocolate cake?
Yes, you can. The chocolate buttercream is my go-to, but if you want to switch things up, peanut butter frosting or my Chocolate Cream Cheese Frosting great alternatives!
Can I long-ferment this sourdough chocolate cake ?
Absolutely! I tested this recipe both as a quick discard and a long-fermented cake. You can find the step-by-step directions in the Notes below.
Can I bake this cake in a 9×13-inch pan?
You sure can! Bake at 350 degrees F for 30-35 minutes. You can also bake this cake batter into 12 cupcakes as well. Fill about 2/3 full and bake for 18-22 minutes.
If you tried this Sourdough Chocolate Cake recipe or any other recipe on my blog, please leave a 🌟 star rating and let me know how it went in the📝 comments below. Thanks for visiting!
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Ingredients
Sourdough Guinness Chocolate Cake
- 180 grams hot water 3/4 cup
- 220 grams all-purpose flour about 1 1/2 cups
- 75 grams unsweetened, natural cocoa powder (not Dutch-processed) 3/4 cup
- 12 grams baking soda 2 teaspoons
- 2 grams espresso powder, optional 2 teaspoons
- 6 grams salt 1 teaspoon
- 200 grams sugar 1 cup
- 220 grams light brown sugar 1 cup
- 180 grams sour cream, room temperature 3/4 cup
- 2 eggs room temperature
- 115 grams neutral oil, like avocado oil 1/2 cup
- 8 grams vanilla extract 2 teaspoons
- 120 grams sourdough discard 1/2 cup
Chocolate Buttercream Frosting
- 226 grams unsalted butter, softened 1 cup
- 400 grams powdered sugar 3 cups + 1 Tablespoon
- 50 grams unsweetened cocoa powder 1/2 cup
- 45 grams heavy cream 3 Tablespoons
- 8 grams vanilla extract 2 teaspoons
- pinch of salt
Instructions
- If you prefer to long-ferment this cake, read the directions in the Notes first! You will prepare parts of the batter the night before.
- Preheat the oven to 350 degrees F and line two 9-inch cake pans with butter and parchment paper. Set to the side
DRY INGREDIENTS
- In a medium mixing bowl, sift together the flour, natural cocoa powder, baking soda, espresso powder and salt. Add the sugars, then whisk until combined. Make sure there are no clumps of brown sugar. Set to the side. Note: Cocoa powder is notorious for having clumps, so be sure to not skip the sifting! This recipe calls for unsweetened natural cocoa powder, not Dutch-processed cocoa powder. The acidity of the natural cocoa powder reacts with the baking soda to help this cake rise.220 grams all-purpose flour, 75 grams unsweetened, natural cocoa powder (not Dutch-processed), 12 grams baking soda, 2 grams espresso powder, optional, 6 grams salt, 200 grams sugar, 220 grams light brown sugar
WET INGREDIENTS
- In a separate bowl, whisk together the room-temperature sour cream, eggs, neutral oil, vanilla extract and sourdough discard until smooth. You can use active sourdough starter, as well. Just be sure to use the same amount in grams.180 grams sour cream, room temperature, 2 eggs, 115 grams neutral oil, like avocado oil, 8 grams vanilla extract, 120 grams sourdough discard
COMBINE
- Pour the wet ingredients into the dry ingredients, then mix with a rubber spatula until there are no more streaks of flour. The batter will look very thick, like brownie batter.
- Pour in the hot water and whisk until combined. This will thin out the cake batter.You want the water to be hot, about 110 degrees F. This helps “bloom” the cocoa powder which will enhance the cocoa flavor.180 grams hot water
- Divide the cake batter evenly into the prepared cake pans. Gently drop the cake pans on the countertop to remove any air bubbles from the batter.
BAKE
- Bake the Sourdough Chocolate Cake for 20-25 minutes. The cake is done when a toothpick comes out mostly clean with a few moist bites of cake.
- Remove the cake from the oven and place on a wire rack to cool completely. Note: It is normal for a chocolate cake to slightly sink in the middle even when it’s been completely baked through. Cocoa powder isn’t as strong as all-purpose flour. There is a lot of moisture in this moist chocolate cake.
CHOCOLATE BUTTERCREAM FROSTING
- In a stand mixer with a whisk attachment, beat the room-temperature butter on medium speed for 2 minutes, or until light and fluffy.This can also be done with a hand mixer.226 grams unsalted butter, softened
- Next, add the powdered sugar, one cup at a time at medium speed.400 grams powdered sugar
- Finally, add the cocoa powder, heavy cream, vanilla and a pinch of salt. Beat of medium high for 2 minutes or until light and fluffy.50 grams unsweetened cocoa powder, 45 grams heavy cream, pinch of salt, 8 grams vanilla extract
- Directions on how to assemble and decorate below.
Notes
How to Long-Ferment Sourdough Chocolate Cake:
- In a medium bowl, add the cocoa powder, then pour in the warm water. Whisk until combined. This helps to “bloom” the cocoa for a more deep chocolate flavor.
- Next, add the flour, white and brown sugar, room temperature sour cream, neutral oil and room temperature sourdough discard. Whisk until everything is smooth. You can also use active sourdough starter, just use the same amount in grams.
- Cover the bowl and place it in the fridge overnight or for 24 hours.
- A few hours before you are ready to bake, pull the cake batter out of the fridge and allow it to come to at least 70 degrees F.
- Once the batter is at least 70 degrees F, add the eggs and vanilla extract, then whisk until smooth.
- Finally, gently fold in the baking soda, espresso powder and salt. Be careful not to overmix the batter.
- Divide the batter between two greased 9-inch cake pans. Gently tap the cake pans on the counter to remove air bubbles.
- Bake at 350 degrees F for 20-25 minutes or until a toothpick comes out with a few moist bites of batter.
- Cool completely on a wire rack before removing from the cake pans and decorating.
Other Cake Sizes
9×13 inch baking pan: Pour into a greased baking pan and bake at 350 degrees F for 30-35 minutes. Cupcakes: This batter makes enough for 12 cupcakes. Fill about 2/3 full and bake at 350 degrees F for 18-22 minutes.How to Decorate
Before decorating, double-check that the cakes are completely cooled! If they are even slightly warm, the frosting will melt into a sugary mess. If the cakes are domed, slice off a thin piece of the top of the cake with a serrated knife to help level the cakes. This helps the cake to lay evenly when layered. First, place the bottom layer on the cake stand. Top with about a cup of the frosting and spread with an offset spatula or flat knife until it is evenly covered. Place the 2nd cake layer on top and cover evenly with another cup of frosting. Cover the edges with the remaining frosting. Leave the cake uncovered for at least 30 minutes to set. This makes for easier and cleaner slicing. I decorated my cake with just the frosting, but here are some other creative ideas for you to try:- Chocolate ganache
- fresh fruit, like berries
- Chocolate shavings or chips
- Chocolate or gold sprinkles
- Macaroons
Nutrition
Serving: 1slice | Calories: 640kcal | Carbohydrates: 91g | Protein: 6g | Fat: 32g | Saturated Fat: 14g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 13g | Trans Fat: 1g | Cholesterol: 81mg | Sodium: 495mg | Potassium: 248mg | Fiber: 4g | Sugar: 68g | Vitamin A: 659IU | Vitamin C: 0.2mg | Calcium: 59mg | Iron: 3mg
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