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Sourdough Blueberry Crumb Cake

Sourdough blueberry crumb cake is a lightly sweetened cake made with sourdough discard, studded with sweet blueberries and topped with a sweet crumb topping. Perfect for breakfast, brunch or a snack, this crumb cake is delicious!
Prep Time 20 mins
Cook Time 1 hr 5 mins
Course Breakfast, Dessert, Snack
Cuisine American
Servings 16 slices

Ingredients
  

Crumb Topping

  • 6 Tablespoons unsalted butter melted
  • 1/3 cup granulated sugar
  • 1 teaspoon vanilla extract
  • 1 teaspoon cornstarch
  • 1/2 teaspoon salt
  • 1 cup all purpose flour

Sourdough Blueberry Cake

  • 1.5 cups all purpose flour
  • 1 Tablespoon cornstarch
  • 1/2 teaspoon baking soda
  • 1 teaspoon baking powder
  • 1/2 teaspoon salt
  • 6 Tablespoons unsalted butter softened
  • 2/3 cup granulated sugar
  • 1 egg
  • 1 egg yolk
  • 2 teaspoons vanilla extract
  • 3/4 cup sourdough discard or bubbly sourdough starter
  • 1/2 cup buttermilk see recipe notes for substitutions
  • 2.5 cups fresh blueberries see recipe note for frozen blueberries

Instructions
 

Crumb Topping

  • Melt 6 Tablespoons of butter. Add the sugar, vanilla, cornstarch, salt and flour. Mix together until it forms a moist, crumbly topping. Set aside the crumb topping for later.

Sourdough Blueberry Cake

  • Preheat oven to 350 degrees.
  • To a small bowl, add the flour, cornstarch, baking soda, salt and baking powder. Fluff together with a fork. Set aside.
  • Using a stand mixer or a handheld mixer, mix together the softened butter and granulated sugar until light and creamy.
  • Add the egg, egg yolk and vanilla. Mix again, scraping the sides and bottom as needed until fully incorporated, light and fluffy.
  • Pour ¾ cup sourdough discard (direct from the fridge or use ripe sourdough starter) and add to the bowl. Mix together.
  • Add the flour mixture and mix until just incorporated. Pour in the buttermilk and mix until smooth.
  • Add 2 cups of fresh blueberries (reserving ½ cup for topping) to the batter and stir lightly to combine. See recipe note if using fresh blueberries.
  • Line an 8 by 8 pan (my favorite, affiliate link) with parchment paper. Pour blueberry cake mixture into the pan and spread evenly.
  • Sprinkle the crumb mixture on top of the cake, spreading it evenly and breaking up clumps with your fingers as you go. Dot the top with the reserved ½ cup of blueberries.
  • Bake the cake for 60-75 minutes until baked through. Once the cake has stopped jiggling in the middle, take a sharp knife and stick it straight in the middle of the cake. If it has batter on it, continue baking a few more minutes. If it comes out clean, the cake is finished baking.
  • Cool and slice to serve. The cake stores well at room temperature for a day or two or can be frozen for longer storage.

Notes

Buttermilk: If you don't have buttermilk on hand, you can substitute 1/4 cup milk mixed with 1/4 cup sour cream.
Blueberries: Fresh blueberries are best for this recipe, but frozen blueberries work too in a pinch. If using frozen blueberries, toss them in 1-2 teaspoons of flour and then gently stir into the batter. This helps the blueberries spread throughout the cake and not sink to the bottom. Using frozen blueberries may also increase the baking time about 10 minutes. 
Keyword blueberry, crumb cake, snack cake