Heat the oven to 350°F. Grease and line two 9-inch round cake pans with parchment.
Whisk flour, cocoa, baking soda, baking powder, and salt in a bowl.
Beat softened butter and sugar until pale and fluffy, about 3 minutes. Beat in eggs one at a time, then vanilla and red coloring.
Add the dry ingredients in three additions, alternating with buttermilk. Mix just until combined, then stir in vinegar.
Divide batter between pans and bake 28 to 32 minutes, until the centers spring back and a toothpick comes out with a few moist crumbs.
Cool cakes in pans for 10 minutes, turn onto racks, and cool completely.
Beat cream cheese and butter until smooth. Gradually beat in powdered sugar and vanilla until creamy.
Trim domed tops if needed, frost one layer, stack the second layer, and frost the top and sides. Chill briefly before slicing.