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Squares of sourdough discard coffee cake arranged on a parchment-lined baking sheet. One square is on its side, showing off its layers of cake and cinnamon streusel.

Sourdough Discard Coffee Cake

Buttery, tender, and irresistibly moist, this sourdough discard coffee cake is layered with crunchy cinnamon streusel and finished with a sweet vanilla glaze. It's perfect for breakfast, brunch, or an anytime treat you won’t be able to stop snacking on!
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Prep Time 30 minutes
Cook Time 45 minutes
Servings: 9 Squares
Course: Afternoon Tea, Breakfast, Brunch
Cuisine: American
Ingredients Method Video

Ingredients
  

Cinnamon Streusel
  • 135 g brown sugar light or dark
  • 95 g all-purpose flour
  • 1 tablespoon ground cinnamon
  • ¼ teaspoon fine sea salt
  • 85 g unsalted butter cold and cut into roughly ½" (1.3 cm) cubes
Cake
  • 170 g all-purpose flour
  • 1 ¼ teaspoons baking powder
  • ½ teaspoon baking soda
  • ½ teaspoon fine sea salt
  • 175 g unsalted butter room temperature
  • 190 g granulated sugar
  • 3 large eggs room temperature
  • 2 ½ teaspoons vanilla extract
  • 100 g sourdough discard or active starter
  • 150 g full-fat sour cream
Vanilla Glaze
  • 120 g powdered sugar AKA 10X, confectioner's, or icing sugar
  • ½ teaspoon pure vanilla extract
  • 2 tablespoons heavy cream, milk, or water

Method
 

Cinnamon Streusel
  1. Preheat the oven to 350˚F (175˚C). To a medium mixing bowl, add 135 g brown sugar, 95 g all-purpose flour, 1 tablespoon ground cinnamon, and ¼ teaspoon fine sea salt. Whisk or use your fingertips to combine.
  2. Add 85 g unsalted butter and work into the flour mixture as if you're making pie crust or biscuit dough, until it resembles bread crumbs. You can use your fingertips, a pastry blender, or even a food processor.
  3. Use your hands to squish the mixture together to make some larger clumps of dough. Spread out onto a baking sheet lined with parchment paper or a silicone baking mat and cover with plastic wrap or a plastic baking sheet cover (affiliate link), and put in the freezer while you make the cake batter.
Cake
  1. Spray an 8"-9" (20–22 cm) square cake pan with baking spray, and line with a rectangle of parchment paper as a sling.
  2. To a medium mixing bowl, add 170 g all-purpose flour, 1 ¼ teaspoons baking powder, ½ teaspoon baking soda, and ½ teaspoon fine sea salt. Whisk to combine.
  3. To a separate mixing bowl, add 175 g unsalted butter (at room temperature), and 190 g granulated sugar. Beat on medium-high speed until light and fluffy, about 3 minutes.
  4. Add 3 large eggs and 2 ½ teaspoons vanilla extract, and beat until combined.
  5. Add 100 g sourdough discard and 150 g full-fat sour cream and mix to combine. Add the dry ingredients and mix on low speed just until combined.
  6. Place about half of the cake batter into the cake pan and spread evenly. Sprinkle on about half of the frozen cinnamon streusel. Put the remaining cake batter on top, and spread evenly. Return the remaining streusel to the freezer. Bake for about 20 minutes or until the cake has risen but is still pale on top.
  7. Gently remove the cake from the oven, and sprinkle the rest of the streusel on top. Return the cake to the oven and bake for another 15-20 minutes or until it's golden brown on top and a toothpick inserted into the center comes out clean (or with just a few crumbs).
  8. Leave the cake to cool in the pan for about 20 minutes, or just until it's cool enough to handle. Carefully remove it using the parchment sling and transfer to a cutting board to cool completely.
Vanilla Glaze
  1. Add 120 g powdered sugar, ½ teaspoon pure vanilla extract, and 2 tablespoons heavy cream, milk, or water to a small mixing bowl, and whisk until completely smooth. You can adjust the consistency of the glaze to your liking: add more liquid for a thinner glaze, or more powdered sugar for a thicker glaze.
  2. After the cake has cooled completely, drizzle the glaze on top. Leave the cake at room temperature for 20–30 minutes to allow the glaze to set before slicing the cake into squares. You can cut it in a 3 x 3 grid for 9 large squares, or a 4 x 4 grid for 16 smaller squares.
  3. If you used water to make the vanilla glaze, you can leave the cake out at room temperature in an airtight container for up to 3 days. If you used milk or cream in the glaze, you should refrigerate the cake after a couple of hours at room temperature.

Video