Sourdough Berry Crumble Bars (Mixed Berry Version)

These Sourdough Berry Crumble Bars are one of my favorite summer desserts because they’re as easy to make as they are beautiful to serve. A buttery shortbread crust is layered with a jammy berry filling and topped with a golden crumble—all made from the same dough, so there’s no extra fuss.

Whether you use fresh berries from the farmers market or frozen berries from the freezer, these bars turn out delicious every time. And if you love fruit-filled desserts with a buttery crust, my Sourdough Apple Pie Bars are another recipe you’ll definitely want to try!

Quick Look: Sourdough Berry Crumble Bars

Prep Time: 20 minutes
Bake Time: 40 minutes
Chill Time: 3 hours
Total Time: 4 hours
Servings: 20 bars
Calories: ~218kcals per bar (based on nutrition panel)
Cook Method: Baked
Flavor Profile: Buttery shortbread base and crumble topping sandwiching a bright, juicy mixed berry filling with a hit of fresh lemon. A patriotic, crowd-pleasing treat perfect for summer BBQs!
Difficulty: Easy — One dough does double duty as the crust and crumble, with simple steps and no special equipment needed!

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Why You’ll Love These Sourdough Berry Crumble Bars

Quick and easy—This recipe is a delicious way to use leftover sourdough starter. It’s fast and uses simple ingredients you probably already have in your kitchen. The base and the crumble topping come from the same dough, so make one batch and split it in two. These Sourdough Lemon Bars use a similar buttery shortbread dough and are just as quick.
Patriotic—The red and blue berries make these bars a natural fit for Memorial Day, the Fourth of July, or any summer cookout. This Sourdough Icebox Cake is another berry dessert you could make to celebrate the day.
Customizable—Use a mix of sweet berries like strawberries, blueberries, and raspberries. Fresh is best, but frozen berries work just fine too. And if you’re craving that same berry flavor in a softer, syrupy form, give my Sourdough Berry Cobbler a whirl, as it’s topped with golden biscuits instead of a crumble.

Ingredients & Substitutions

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

Sourdough Crust

Unsalted Butter – That buttery shortbread crust won’t happen without butter. Use melted butter for easy mixing.
Flour—I used all-purpose flour to make this tender crust.
Sourdough Discard—For sweeter recipes like these sourdough bars, I like to use 1–2 day-old discard. You can use active sourdough starter, but be sure to measure the exact same amount in grams.

Berry Filling

Berries—I used a mix of strawberries, blueberries, and raspberries, but feel free to mix and match based on what you like. Blackberries work great, too. If you’re using frozen berries, make sure to thaw and drain them first.
Lemon—A little fresh lemon juice and zest brighten up the berry flavor. You need to zest the yellow part of the peel, not the white pith underneath, because that part turns bitter.
Cornstarch—Cornstarch helps to thicken the fruit filling while giving the finished product a smooth, glossy finish. You could also substitute 1:1 with arrowroot starch (powder) or tapioca starch/tapioca flour. If your fruit is extra ripe or frozen, you might need a touch more thickener, about 1 to 2 grams, no matter which one you’re using.

How to Make Mixed Berry Sourdough Crumble Bars

Preheat the oven to 350°F and line a 9×13 baking dish with parchment paper. Set aside.

In a medium bowl, add the melted butter, sourdough discard, and vanilla. Whisk until combined. Set aside.

In a separate bowl, whisk together the dry ingredients: flour, sugar, baking powder, and salt.

Add the wet ingredients to the flour mixture and mix until it resembles soft cookie dough.

Dump ⅔ of the dough into the prepared baking dish and gently press the dough with your hands. Bake for 12-15 minutes, or until the shortbread base turns golden brown.

In a medium bowl, add the berries, sugar, lemon juice, lemon zest, and cornstarch. Mix until everything is combined.

Once the crust is partially baked, remove the pan from the oven and let it cool for 5 minutes.

Pour the berry mixture over the hot base layer.

adding the crumble on top of the berry mixture

Then crumble the rest of the dough on top.

Continue to bake for another 30-40 minutes or until the crumble topping turns golden brown and the berry filling is bubbling.

Remove the Sourdough Crumble Bars from the oven and place them on a wire rack to cool for at least 1 hour, then for 2 hours in the fridge for them to set. The chill time is crucial for allowing the filling to set and for easy slicing. Slice and enjoy!

McKenna’s Helpful Tips

Don’t skip the chill time, or you’ll end up with a gooey mess instead of clean slices.
Line your baking dish with parchment paper so the bars lift out clean and easy.
Use your favorite fruit, fresh or frozen. Fresh blueberries, raspberries, strawberries, or even blackberries.
Long fermentation: Prep the dough, cover it, and store in the fridge for up to 3 days. Before baking, take it out and let it come to room temperature for about 15 minutes.

How to Store

Cover any leftover bars and keep them in the fridge for up to 4 days. If you want to freeze them, wrap each bar tightly in plastic wrap, toss them in a freezer bag, and they’ll keep for up to 3 months. Let them thaw in the fridge overnight before you dig in.

Sourdough Berry Crumble Bars FAQs

Can I use frozen berries for these sourdough crumble bars?

Yes, you can. Thaw and drain the berries first, though. Frozen berries hold extra moisture, and skipping this step will leave you with a soggy, gummy base. Pat them dry with a paper towel before mixing them in. You can use fresh or frozen cherries for my Sourdough Cherry Cobbler!

Can I make these blueberry bars ahead of time?

You sure can make the dough ahead of time! Cover the crumble bar dough and keep it in the fridge until you’re ready to bake. You can do the same thing for my Sourdough Lemon Bars! But these crumble bars are best served on the first day. The crumble topping softens after about a day, so the bars don’t hold up well if baked too far in advance.

Do I have to use all three berries?

No, use whatever you like! Go with just one or two favorites, or even throw in some blackberries. Just make sure you’ve got 650 grams of berries total so the filling turns out right. I love mix and matching berries in my Sourdough Berry Cobbler as well!

More Sourdough Bar Recipes

Sourdough Apple Pie Bars with Salted Caramel

Sourdough Magic Chocolate Bars Recipe {Pure Delight!}

Easy Sourdough Lemon Bars (Discard Recipe)

Easy Sourdough Discard Banana Bars Recipe

If you tried this Sourdough Berry Crumble Bars 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!