Moist Sourdough Chocolate Sheet Cake with Chocolate Buttercream
A rich and moist chocolate sheet cake made with sourdough discard, topped with a smooth and creamy chocolate buttercream. Perfect for any occasion, this easy-to-make cake stays soft for days and is full of deep chocolate goodness.
Calories 350kcal
Ingredients
- 240 g sourdough discard 1 cup
- 7 g baking soda 1½ tsp
- 190 g all-purpose flour 1½ cups
- 75 g cocoa powder ¾ cup
- 5 g baking powder 1 tsp
- 3 g salt ½ tsp
- 200 g powdered sugar 1 cup
- 160 g neutral oil (avocado, vegetable, or melted coconut) ¾ cup
- 2 eggs
- 5 g vanilla extract 1 tsp
- 120 g milk ½ cup
- 120 g hot coffee ½ cup
Chocolate Buttercream Ingredients
- 170 g unsalted butter, softened ¾ cup
- 40 g cocoa powder ⅓ cup
- 300 g powdered sugar 2½ cups
- 60 g heavy cream or milk ¼ cup
- 5 g vanilla extract 1 tsp
- 1 g salt ¼ tsp
Instructions
- Preheat the Oven – Set your oven to 175°C (350°F) and grease a 9x13-inch baking pan.
- Activate the Discard – In a small bowl, mix sourdough discard and baking soda; let it sit while you prepare the rest of the ingredients.240 g sourdough discard, 7 g baking soda
- Mix the Dry Ingredients – In a separate bowl, whisk together flour, cocoa powder, baking powder, and salt.190 g all-purpose flour, 75 g cocoa powder, 5 g baking powder, 3 g salt
- Combine the Wet Ingredients – In a large mixing bowl, whisk granulated sugar, oil, eggs, vanilla, and milk until smooth. Stir in the activated discard mixture.200 g powdered sugar, 160 g neutral oil (avocado, vegetable, or melted coconut), 2 eggs, 5 g vanilla extract, 120 g milk
- Add the Dry Ingredients – Gradually mix the dry ingredients into the wet mixture, stirring gently.
- Incorporate the Coffee – Pour in hot coffee, mixing until fully combined.120 g hot coffee
- Bake – Pour the batter into the prepared pan and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool completely before frosting.
Make the Chocolate Buttercream:
- Beat the Butter – In a mixing bowl, beat butter until light and creamy.170 g unsalted butter, softened
- Add Cocoa and Sugar – Sift in cocoa powder and powdered sugar, mixing until fully combined.40 g cocoa powder, 300 g powdered sugar
- Adjust Consistency – Gradually add heavy cream or milk, one tablespoon at a time, until the buttercream is smooth and spreadable.60 g heavy cream or milk
- Final Touches – Mix in vanilla extract and a pinch of salt to bring everything together.5 g vanilla extract, 1 g salt
Assembling the Cake
- Once the cake is completely cool, spread the chocolate buttercream evenly over the top. Slice and enjoy!