Sourdough Guinness Chocolate Cake Recipe (with Discard)

Sourdough Guinness Chocolate Cake is rich, moist, and easy to make with sourdough discard, Guinness, and chocolate cream cheese frosting.

This Sourdough Guinness Chocolate Cake is everything a chocolate cake should be—rich, moist, and packed with deep chocolate flavor!

The Guinness and a little espresso powder make the chocolate taste even bolder, while the sourdough discard adds a subtle tang that keeps things interesting. 

And the chocolate cream cheese frosting? Pure magic.

Even better, it’s a one-bowl recipe, so you won’t be stuck with a pile of dishes. Whether you’re into sourdough or just love a rich, chocolatey dessert, this one’s a keeper. Chocolate lovers are gonna love it!

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Why You’ll Love This Recipe

Flavor

This cake has a deep, rich chocolate flavor with a slight tang from the sourdough discard that keeps it interesting. The stout and espresso powder work together to enhance the chocolate, making each bite bold and satisfying. The cream cheese frosting adds the perfect balance of sweetness and tang, making this cake truly unforgettable.

Moist

Thanks to the sourdough discard and the right balance of ingredients, this cake stays incredibly moist for days. Even after a few days in the fridge, it remains soft and tender, making it a great make-ahead dessert. You won’t have to worry about it drying out, even if you bake it ahead of time for a special occasion.

Easy

This is a one-bowl recipe that makes cleanup a breeze while still serving up a bakery-quality cake. You get all the flavor and texture of a rich chocolate cake without the hassle of using a bunch of bowls and extra dishes. It’s a fantastic option for beginner bakers as well as experienced sourdough fans who want an easy, impressive dessert.

Ingredients Needed

Guinness beer: To get the most robust flavor out of this dark stout beer, I prefer to reduce the Guinness. Save a small amount of the reduction for the chocolate cream cheese frosting, as well!

Flour: I used sifted all-purpose flour, but unbleached cake flour is another excellent choice for soft and tender cake. If you are 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. The acidity of the natural cocoa powder reacts with the baking soda to help this cake rise. 

Baking soda: Make sure that your baking soda is fresh and active. Note that the Sourdough Guinness Chocolate Cake will not rise if it is expired.

Sugar: I used white sugar, but you can substitute it with others, like coconut sugar.

Espresso powder (optional): Adding espresso powder to this cake helps to enhance the rich chocolate flavor.

Salt: Any unrefined salt will do, but my favorite is Redmond’s unrefined salt for some extra minerals.

Oil: You can use any neutral oil; my favorite is avocado oil.

Eggs: Bring eggs to room temperature quickly by placing them in a bowl of hot water for at least 5 minutes. 

Milk: Bring the milk to room temperature quickly by heating it up for 15-20 seconds in a microwave-safe bowl.

Sourdough discard: I like using active sourdough starter for many recipes, but for sweet recipes like this cake, I prefer sourdough discard that’s no older than a few days old

Vanilla extract: Use pure vanilla extract, rather than imitation vanilla, for the best flavor.

Chocolate Cream Cheese Frosting

Cream cheese: For the easiest mixing, it is important that the cream cheese is at room temperature before mixing. 

Unsalted butter: Use softened butter for the most creamy and smooth frosting.

Cocoa powder – Unsweetened natural or Dutch-processed cocoa powder can be used.

Powdered sugar: Add the powdered sugar one cup at a time while mixing to prevent sugar from flying everywhere.

Vanilla extract: Again, for the best vanilla flavor, use pure vanilla extract instead of imitation.

Pinch of salt: A small amount helps balance the sweetness and enhance the chocolate flavor.

* To find precise measurements, scroll to the bottom of this post to find the recipe card*

Supplies

• Large mixing bowls
• Kitchen Scale
• Two 9-inch cake pans or 9×13 baking dish
• Parchment paper
• Wire rack

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How to Make This Chocolate Guinness Cake

Preheat the oven to 350 degrees F and line two 9-inch cake pans with butter and parchment paper. Set to the side.

GUINNESS

Before mixing together the cake batter, prepare the reduced Guinness.

In a small saucepan, bring the dark beer to boil over medium-high heat. Once it is boiling, reduce the heat to medium-low and allow it to simmer until it is reduced to 220 grams (¾ cup + 4 teaspoons), about 30 minutes. 

You will use 180g (3/4 c) of the reduced Guinness for the cake batter. Be sure to set aside some of the reduced Guinness for the frosting. (40 grams or 4 teaspoons)

While the Guinness is simmering, start to prepare the cake batter.

DRY INGREDIENTS

In a medium mixing bowl, sift together the flour, natural cocoa powder, baking soda, espresso and salt. Add the sugar, then whisk until combined. Set to the side. 

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. 

WET INGREDIENTS

In a separate bowl, whisk together the room-temperature sour cream, eggs, oil, vanilla extract and sourdough starter discard until smooth. 

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, reduced Guinness and whisk until combined. This will thin out the cake batter.

You want the Guinness to be hot. This helps “bloom” the cocoa powder which will enhance the cocoa flavor. 

Divide the cake batter evenly into the prepared cake pans. Drop the cake pan on the countertop to remove any air bubbles from the batter.

BAKE

Bake the Sourdough Guinness 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.

HOW TO MAKE CHOCOLATE CREAM CHEESE  FROSTING

In a stand mixer with a whisk attachment, beat the room-temperature butter and softened cream cheese on medium speed for 2 minutes, or until light and fluffy.

Next, add the powdered sugar, one cup at a time at medium speed.

Finally, add the cocoa powder, reduced Guinness and a pinch of salt. Mix until combined. 

Prefer a Bailey’s Irish Cream Buttercream Frosting instead? See my recipe in the notes below!

How to Decorate

Before decorating, double-check that the cakes are completely cooled. Why a completely cooled cake? 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. 

For this sourdough chocolate cake recipe, 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

How to Store

Leftover Sourdough Guinness Chocolate Cake should be stored in an airtight container in the fridge for up to 5 days, but it is best served at room temperature. Remove the cake from the fridge at least 1 hour before serving. 

This cake freezes beautifully. Once the cake has cooled, cover it tightly with plastic wrap, place it in a freezer-safe bag, and freeze for up to 3 months. When ready to serve, bring the room temperature and decorate as described above.

How to Serve

Serve Sourdough Guinness Chocolate Cake at room temperature for the best texture and flavor. If it’s been refrigerated, let it sit out for at least an hour before serving. Most people enjoy it as-is, but you can also add a dollop of whipped cream, a scoop of vanilla ice cream, or a drizzle of chocolate ganache. For a festive touch, dust it with powdered sugar or top with fresh berries.

FAQs

What’s a good variation of this cake?

If you love warm spices, add a touch of cinnamon and nutmeg for a gingerbread cake twist. I’ve also included my Bailey’s Buttercream Frosting recipe below in the notes!

What’s a fun way to serve this cake?

For a St. Patrick’s Day treat, serve slices with a scoop of vanilla ice cream and a drizzle of warm chocolate sauce. Or, turn it into a sourdough surprises moment by stacking layers with alternating frostings, like cream cheese and chocolate buttercream frosting for an extra indulgent twist.

Can I use a different type of oil?

Yes, you can swap vegetable oil for olive oil if you prefer a slight fruity note, but it may alter the cake’s flavor slightly.

Can I bake this in a different pan?

Yes! Instead of two 9-inch round pans, you can use a springform pan for easy removal or bake it as a bundt cake for a more decorative presentation. If you go for a 9×13 pan, expect a slightly different bake time. Check it with a cake tester to make sure it’s done.

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