Sourdough Rhubarb Streusel Coffee Cake
A delicious and easy coffee cake featuring tangy rhubarb, a moist sourdough discard cake base, and a buttery cinnamon streusel topping. The perfect way to use up sourdough discard and celebrate spring flavors!
Equipment
- 9x9 inch square baking pan (or 8x8 inch for a thicker cake)
- Mixing bowls (large, medium, small)
- Whisk
- Electric mixer (handheld or stand mixer with paddle attachment)
- Rubber Spatula
- Measuring Cups and Spoons
Ingredients
For the Rhubarb Layer:
- 3 cups 300-350g fresh rhubarb, washed and diced into ½-inch pieces
- 2 tablespoons granulated sugar
- 1 teaspoon orange zest (optional)
For the Sourdough Streusel Topping:
- ¾ cup 90g all-purpose flour
- ½ cup 100g light brown sugar, packed
- 1 ½ teaspoons ground cinnamon
- ¼ teaspoon ground ginger or cardamom (optional)
- 6 tablespoons 85g unsalted butter, cold and cubed
- 2 tablespoons sourdough discard (unfed)
- ½ cup chopped pecans or walnuts (optional)
For the Sourdough Cake Batter:
- 1 ¾ cups 210g all-purpose flour
- 1 ½ teaspoons baking powder
- ½ teaspoon baking soda
- ½ teaspoon salt
- ½ cup 113g unsalted butter, softened to room temperature
- ¾ cup 150g granulated sugar
- 2 large eggs at room temperature
- 1 cup 220-240g sourdough discard, (unfed), room temperature
- 1 ½ teaspoons vanilla extract
- ¼ cup 60ml milk or buttermilk, at room temperature
Instructions
- Prepare Rhubarb & Preheat Oven:
- Preheat oven to 375°F (190°C). Grease and flour your 9x9 inch baking pan, or line with parchment paper, leaving an overhang.
- In a medium bowl, combine the diced rhubarb, 2 tablespoons of granulated sugar, and optional orange zest. Toss gently and set aside.
- Make the Sourdough Streusel Topping:
- In a separate medium bowl, whisk together the ¾ cup all-purpose flour, ½ cup light brown sugar, 1 ½ tsp cinnamon, and optional ginger/cardamom for the streusel.
- Add the 6 tbsp cold, cubed butter and 2 tbsp sourdough discard. Using your fingertips or a pastry blender, cut the butter and discard into the dry ingredients until the mixture resembles coarse crumbs.
- If using, stir in the ½ cup chopped nuts. Place the streusel mixture in the refrigerator.
- Prepare the Cake Batter:
- In another medium bowl, whisk together the 1 ¾ cups all-purpose flour, 1 ½ tsp baking powder, ½ tsp baking soda, and ½ tsp salt. Set aside.
- In a large bowl, using an electric mixer, cream the ½ cup softened butter and ¾ cup granulated sugar together until light and fluffy (about 2-3 minutes).
- Beat in the 2 large eggs one at a time, mixing well after each. Scrape down the sides of the bowl.
- Stir in the 1 cup sourdough discard and 1 ½ tsp vanilla extract until just combined.
- Add half of the dry ingredient mixture to the wet ingredients and mix on low speed until just barely combined. Pour in the ¼ cup milk/buttermilk and mix on low. Add the remaining dry ingredients and mix on low speed only until no dry streaks of flour remain. Do not overmix.
- Assemble and Bake:
- Spread half of the cake batter evenly into the prepared baking pan.
- Drain any excess liquid from the macerated rhubarb. Evenly distribute the rhubarb pieces over the batter.
- Spoon or gently spread the remaining cake batter over the rhubarb layer.
- Evenly sprinkle the chilled streusel topping over the batter.
- Bake for 45-55 minutes, or until a toothpick inserted into the center of the cake portion comes out clean or with a few moist crumbs. The top should be golden brown. (If streusel browns too quickly, loosely tent with foil for the last 10-15 mins).
- Cool and Serve:
- Let the coffee cake cool in the pan on a wire rack for at least 20-30 minutes before slicing and serving.
- Serve warm or at room temperature.
Notes
Room Temperature Ingredients: Ensure eggs, butter, sourdough discard, and milk are at room temperature for the best cake texture.
Do Not Overmix: Mix batter only until ingredients are just combined to prevent a tough cake.
Frozen Rhubarb: If using frozen rhubarb, do not thaw completely. Toss diced frozen rhubarb with 1 tablespoon of all-purpose flour before adding to the batter. Baking time may increase slightly.
Storage: Store in an airtight container at room temperature for up to 3 days, or refrigerated for up to 5 days. Freezes well for up to 3 months; wrap tightly.
Do Not Overmix: Mix batter only until ingredients are just combined to prevent a tough cake.
Frozen Rhubarb: If using frozen rhubarb, do not thaw completely. Toss diced frozen rhubarb with 1 tablespoon of all-purpose flour before adding to the batter. Baking time may increase slightly.
Storage: Store in an airtight container at room temperature for up to 3 days, or refrigerated for up to 5 days. Freezes well for up to 3 months; wrap tightly.