For the red velvet batter
2 1/2 cups sifted cake flour
1 teaspoon baking powder
1 teaspoon salt
2 tablespoons cocoa powder (unsweetened)
2 ounces red gel food coloring
1/2 cup unsalted butter, at room temperature
1 1/2 cups sugar
2 eggs, at room temperature
1 teaspoon vanilla extract
1 cup buttermilk, at room temperature
1 teaspoon white vinegar
1 teaspoon baking soda
for the vanilla batter
1 3/4 cups all-purpose flour
1 1/2 teaspoons baking powder
3/4 teaspoons table salt
1 cup granulated sugar
1 1/2 sticks unsalted butter, softened but slightly cool, cut into 12 pieces
3 large eggs
3/4 cups milk
2 teaspoons vanilla extract
for the frosting
12 ounces (1 1/2 packages) cream cheese, at room temperature
1 stick unsalted butter, at room temperature
2 teaspoon pure vanilla extract
3 cups confectioners sugar
Preheat oven to 350F. Line muffin pan with cupcake liners (note that this makes a large batch of cupcakes, approximately 30)
Make your batters; first the vanilla. In the bowl of your stand mixer, combine the flour, baking powder, salt, and sugar on low speed. Add the butter, 1 piece at a time, and combine until the mixture resembles coarse sand. Add the eggs, 1 at time, and mix until fully combined. Add the milk and vanilla, increase the speed to medium, and mix until the batter is light, fluffy and free of lumps.
For the red velvet, sift together the cake flour, baking powder, and salt into a medium bowl; set aside. In a small bowl, mix food coloring and cocoa powder to form a thin paste without lumps; set aside. In the bowl of your stand mixer, beat butter and sugar together until light and fluffy, about 3-4minutes. Beat in eggs, one at a time, then beat in vanilla and the red cocoa paste, scraping down the bowl with a spatula as you go. Add one third of the flour mixture to the butter mixture, beat well, then beat in half of the buttermilk. Beat in another third of flour mixture, then second half of buttermilk. End with the last third of the flour mixture, beat until well combined, making sure to scrape down the bowl with a spatula. In a small bowl, mix vinegar and baking soda. Yes, it will fizz! Add it to the cake batter and stir well to combine.
Using alternating spoonfuls of red velvet and vanilla, fill your cupcake lines 2/3 full. Bake for 20-22 minutes, until a toothpick inserted in the middle comes out clean.
For the frosting, cream the cream cheese, butter, and vanilla in the bowl of your stand mixer. Add the sugar and beat until smooth. When the cupcakes are cool, frost them generously and serve.