Sourdough Discard Chocolate Cake
This deeply fudgy, incredibly moist chocolate cake uses sourdough discard to add a subtle tang and boost the chocolate flavor. Topped with a silky chocolate buttercream, it's a showstopping dessert that turns kitchen waste into a bakery-worthy treat.
Equipment
- Two 9-inch (23cm) round cake pans
- Parchment paper - For lining the pans
- Large mixing bowl
- Medium mixing bowl
- Digital kitchen scale
- Whisk
- Rubber spatula
- Hand mixer or stand mixer - For the frosting
- Toothpick or cake tester
- Wire cooling rack
- Offset spatula
- Sifter or fine mesh strainer
- Measuring cups and spoons
Ingredients
- 1 cup sourdough discard - 240g, room temperature
- 2 cups all-purpose flour - 250g
- 2 cups granulated sugar - 400g
- ¾ cup Dutch-process cocoa powder - 75g, sifted
- 2 tsp baking soda
- 1 tsp baking powder
- 1 tsp fine sea salt
- 2 large eggs - room temperature
- 1 cup full-fat buttermilk - 240ml, room temperature
- 1 cup strong brewed coffee - 240ml, cooled slightly (or hot water)
- ½ cup neutral vegetable oil - 120ml, such as canola or avocado oil
- 2 tsp pure vanilla extract
For the Chocolate Buttercream Frosting
- 1 cup unsalted butter - 225g, softened to room temperature
- 3 cups powdered sugar - 360g, sifted
- ¾ cup Dutch-process cocoa powder - 75g, sifted
- ¼ cup heavy cream - 60ml, plus more as needed
- 1 tsp pure vanilla extract
- 1 pinch fine sea salt
Instructions
- Preheat oven to 350°F (175°C). Grease two 9-inch round cake pans, line bottoms with parchment, and grease parchment.
- Sift together flour, cocoa powder, baking soda, baking powder, and salt in a large bowl. Whisk to combine.
- In a separate bowl, whisk hot coffee with 2 tablespoons of the sifted cocoa powder until smooth. Set aside to cool slightly.
- In another large bowl, whisk sugar and oil together. Add eggs one at a time, then mix in sourdough discard, buttermilk, and vanilla until smooth.
- Add the coffee-cocoa mixture to the wet ingredients, then add all dry ingredients at once. Fold gently just until no dry streaks remain. Do not overmix.
- Divide batter evenly between the two prepared pans. Tap pans on counter to release air bubbles.
- Bake for 30-35 minutes at 350°F (175°C), until a toothpick inserted in center comes out clean. Cool in pans for 15 minutes, then invert onto wire racks and cool completely.
- Beat softened butter with a hand mixer on medium speed for about 3 minutes until pale and fluffy. Sift in powdered sugar and cocoa powder alternately, then add cream, vanilla, and salt. Beat on medium-high for 3-4 minutes until smooth.
- Place one cooled cake layer on a serving plate. Spread a generous layer of frosting on top. Add the second layer and apply a thin crumb coat over the entire cake. Refrigerate for 15 minutes.
- Apply the remaining frosting generously over the top and sides of the cake. Smooth with an offset spatula. Let rest at room temperature for 30 minutes before slicing and serving.
Notes
- Room Temperature Ingredients: Take eggs, buttermilk, and sourdough discard out of the fridge 45-60 minutes before baking for best results.
- Weigh Your Flour and Cocoa: For consistent results, use a kitchen scale to measure the flour and cocoa powder.
- Don't Skip the Coffee: You won't taste coffee in the finished cake. It intensifies the chocolate flavor dramatically.
- Use Fresh Leavening: Old baking soda and baking powder can cause flat, dense cakes. Check expiration dates before starting.
- Avoid Overmixing: Once you add the dry ingredients, mix only until just combined to prevent a tough, rubbery crumb.
- Cool Completely Before Frosting: Even a slightly warm cake will melt the buttercream. Allow at least 1-1.5 hours for cooling.
- Make-Ahead: Cake layers can be baked 2 days ahead and stored wrapped at room temperature. Frosting can be made 3 days ahead and refrigerated.
- Storage: Store frosted cake at room temperature for up to 2 days or in the refrigerator for up to 5 days. Unfrosted layers freeze well for up to 3 months.