For the cake: Preheat the oven to 350 degrees F. Lightly grease and flour two 8-inch round cake pans.
In a large bowl, sift together the flour, cocoa powder, baking soda and salt. In the bowl of a stand mixer fitted with the whisk attachment, add the oil, granulated sugar, buttermilk, brown sugar, food coloring, vanilla, vinegar and eggs. Mix on low speed until combined. With the mixer running, add the dry ingredients, one cup at a time, to the wet ingredients until just combined. Divide the cake batter evenly between the prepared cake pans. Bake until a toothpick or cake tester inserted in the center of the cakes comes out clean, about 30 minutes.
Transfer the pans to a cooling rack to cool for 10 minutes. Remove the cakes from the pans; if necessary, run a knife along the edges of the pan to help. Place the cakes on the rack and cool to room temperature.
For the frosting: In a large mixing bowl using a hand mixer, or the bowl of a stand mixer fitted with a whisk, beat together the confectioners' sugar, butter and cream cheese. Add 1 tablespoon of the milk and the vanilla. Gradually beat in just enough of the remaining milk to make the frosting smooth and spreadable. Beat at high speed until light and fluffy.
Place one of the cakes on a serving plate and top with a layer of the frosting. Place the second cake on top, and use the remaining frosting to cover the top and sides of the cake. Serve at room temperature.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.