Preheat oven to 350°F. Grease three 9-inch round cake pans. Set aside.
Add the flour, cocoa powder, baking soda, and salt to a large bowl and whisk until combined.
3½ cups all-purpose flour, ¼ cup unsweetened cocoa powder, 1½ teaspoons baking soda, 1 teaspoon kosher salt
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, vegetable oil, and sugar together until smooth.
½ cup unsalted butter, 1¼ cups vegetable oil, 2½ cups granulated sugar
Add in the sour cream, milk, eggs, and vanilla extract and beat until smooth. Add in the red food coloring and beat until fully incorporated.
1 cup sour cream, ¾ cup milk, 3 large eggs, 1 tablespoon pure vanilla extract, 2 tablespoons red food coloring
Add the dry ingredients to the wet ingredients and mix until just combined.
Divide the batter evenly among the 3 cake pans (about 634 grams per pan).
Bake for 25-30 minutes, or until a toothpick inserted in the center of the cake comes out clean. Let the cake cool for at least 10 minutes.