Heat oven to 350℉/77℃.
Spray three 6-inch pans with baking spray. Set aside.
In a medium bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
Combine butter and sugar in a large bowl.
Beat with an electric mixer until light and fluffy, about 2-3 minutes.
Add eggs, one at a time beating well after each addition.
Add flour mixture alternately with buttermilk, beginning and ending with flour mixture.
Mix in vanilla, vinegar, and food coloring.
Divide among prepared pans.
Bake for 25 minutes, or until cakes test done.