Sourdough Vanilla Sheet Cake

5 from 1 vote

Sourdough Vanilla Sheet Cake

The perfect cake for any celebration! It's light and fluffy and topped with a vanilla buttercream frosting (and sprinkles to suit any occasion). Served straight from the baking pan, it's perfect for a crowd!

Prep Time30

Cook Time35

Cooling Time1

Total Time2 5

Course: Dessert

Cuisine: American

Servings: servings

Calories: 292kcal

Author: Jessica Vogl

Equipment

Ingredients

For the Cake

1 ¼ cups all-purpose flour
2 Tablespoons cornstarch
1 ½ teaspoons baking powder
½ teaspoon baking soda
½ teaspoon kosher salt
¾ cup unsalted butter softened
1 ½ cups granulated sugar
200 grams (about ¾ cup) sourdough discard unfed, at room temperature
3 eggs room temperature
⅓ cup sour cream non-dairy or regular dairy
¼ cup milk room temperature, non-dairy or regular dairy
2 teaspoons vanilla extract

For the Buttercream Frosting

1 cup unsalted butter softened
3 ½ cups confectioner's sugar
2 Tablespoons milk non-dairy or regular dairy
2 teaspoons vanilla extract
Sprinkles optional

US Customary - Metric

Instructions

Preheat oven to 325℉ (165℃). Spray a 9x13-inch baking pan with cooking spray, then line with parchment paper to cover the bottom of the pan. Spray the top of the parchment paper with cooking spray again. Set aside.
In a medium-sized bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt. Set aside.
In a large bowl, use a hand-held mixer to cream together the butter and the sugar until light and fluffy, about 2-3 minutes. Add the sourdough discard, eggs, sour cream, milk, and vanilla. Mix until smooth and combined.
Add the dry ingredients into the wet ingredients and mix until smooth and combined. Pour the cake batter into the prepared baking pan. If needed, jiggle the pan to distribute the batter evenly.
Bake for 30-35 minutes or until the cake is set and lightly browned at the edges. A toothpick inserted in the center of the cake should come out clean.
Set the cake in the baking pan on a wire rack to cool fully (at least an hour) before frosting.
To make the frosting, use a hand-held mixer to cream the butter in a medium-sized bowl until light and smooth, 2-3 minutes. Slowly mix in the confectioner's sugar. Add the milk and vanilla extract and mix until fully smooth and incorporated. Add more milk if you feel that the frosting in too thick.
Spread the cooled cake with a layer of frosting, then top with sprinkles (optional). Slice and serve the cake directly from the baking pan.

Notes

To make this recipe with active sourdough starter, replace the sourdough discard with active starter (200g). You do not need to change any other ingredients in the recipe.

Nutrition