Ingredients:
For the Cake:
2 1/2 cups (315g) all-purpose flour
2 tablespoons cocoa powder
1 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1/2 cup (115g) unsalted butter, softened
1 1/2 cups (300g) granulated sugar
2 large eggs, at room temperature
1 cup (240ml) buttermilk, at room temperature
1 tablespoon white vinegar
2 teaspoons vanilla extract
1 teaspoon purple gel food coloring
For the Cream Cheese Frosting:
8 ounces (225g) cream cheese, softened
1/2 cup (115g) unsalted butter, softened
4 cups (480g) powdered sugar, sifted
2 teaspoons vanilla extract
Pinch of salt
Directions:
Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
In a large bowl, beat the butter and sugar together on high speed until creamy and fluffy, about 3 minutes. Add the eggs one at a time, beating well after each addition.
In a small bowl, combine the buttermilk, vinegar, vanilla extract, and purple food coloring.
With the mixer on low speed, add the dry ingredients to the butter mixture in three additions, alternating with the buttermilk mixture, beginning and ending with the dry ingredients. Mix until just combined.
Divide the batter evenly between the prepared pans and smooth the tops. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Cool the cakes in the pans for 10 minutes, then remove them from the pans and transfer to wire racks to cool completely.
To make the frosting, beat the cream cheese and butter together on high speed until smooth and creamy, about 2 minutes. Gradually add the powdered sugar, vanilla extract, and salt. Beat on high speed for 3 minutes until light and fluffy.
Assemble the cake by placing one layer on a serving plate. Spread an even layer of cream cheese frosting on top. Repeat with the second layer. Frost the top and sides of the cake with the remaining frosting.
Decorate as desired and serve.