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Sourdough Blueberry Crumb Cake

  • Author: Emilie Raffa
  • Prep Time: 15 minutes
  • Cook Time: 55-65 minutes
  • Total Time: 70-80 minutes
  • Yield: One 8x8-inch cake
  • Category: Sourdough Discard Recipes
  • Method: Baking
  • Cuisine: American
  • Diet: Vegetarian


This Sourdough Blueberry Crumb Cake is the perfect treat to make for brunch and weekend breakfasts. With an easy, make-ahead topping, browned butter, and a rich sour cream base there’s no way you’ll pass on a second slice! Don’t forget to check out my notes below for best results. Enjoy!


Crumble Topping

1/4 cup (50g) sugar

1/2 cup (100g) light brown sugar

1 1/2 cups (180g) all purpose flour, spooned and leveled

Rounded 1/2 tsp cinnamon (use 1 tsp for more flavor)

Pinch of fine sea salt

8 tbsp or 1 stick (113 g) salted butter, cut into small cubes, cold

Wet Ingredients

8 tbsp or 1 stick (113 g) salted butter

1 cup (200 g) sugar

1 large egg

1/2 cup (120g) leftover sourdough starter discard (see note below)

Dry Ingredients

2 cups (240 g) all purpose flour, spooned and leveled

1 tsp. baking powder

1/2 tsp baking soda

Pinch of fine sea salt

1/2 cup (120g) sour cream

1 heaping cup of fresh blueberries

Powdered sugar


Preheat the oven to 350 F. Lightly oil an 8×8-inch pan and line with parchment paper. Smooth the bottom and sides of the pan so the paper is flat.

Add the blueberries to a small bowl. Sift a a tablespoon of powdered sugar over the top and gently toss to combine. This will prevent the berries from sinking into the cake. Set aside.

To make the crumble topping, add all of the ingredients to a medium-sized bowl. Mix into crumbles using your hands. The butter should be well blended into to the flour; some larger pieces are ok. If using frozen crumble topping, remove it from the freezer now.

In a small skillet, melt the butter until light golden brown around the edges (you are not fully browning the butter). This will only take a few minutes, but do not walk away from the pan- it will burn quickly!

Meanwhile, using a stand mixer, beat the sugar, egg, and sourdough starter on medium-low speed, 1 minute. With the machine running, gradually pour in the warm melted butter.

In a separate bowl, sift the dry ingredients. Add to the wet ingredients and mix on low speed until just combined. You should still see specks of flour in the bowl; do not over mix. Add the sour cream and mix until smooth. This technique will give the cake a soft, velvety texture. The batter will be thick.

Spoon the batter into the pan. In an even layer, scatter some of the crumbles over the top first, then do a layer of blueberries. Repeat to finish all of the crumbles and blueberries. See my note on this below.

Bake for 55-65 minutes or until a toothpick comes out clean when inserted (I use a dried piece of spaghetti). Please check at the 50 minute mark to see how things are going.

Cool completely before serving. Dust with powdered sugar.


For best results, use leftover 100% hydration starter. Its batter-like texture is the perfect match for this crumb cake. If you’re using a thicker, low hydration starter you will have to add more liquid, otherwise the cake might become more dense.

If you’re not weighing your ingredients, spoon and level the flour into measuring cups. This way, you won’t be tempted to overpack the flour which will result in a denser cake.

When adding the crumble topping and blueberries, make sure to evenly cover the surface of the batter, especially the corners. Otherwise, the batter will puff up in certain spots, which could lead to uneven baking.

Keywords: crumb cake, sourdough crumb cake, crumb cake recipe, blueberries, blueberry crumb cake, sourdough discard, sourdough starter