Preheat the oven to 350ºF (180ºC). Line two 8 or 9-inch (20 or 22-cm) round cake pans with parchment paper. Butter and dust with cocoa powder. You can also lightly grease with baking spray with flour, if you prefer.
Sift flour, baking powder, baking soda, cocoa powder, and salt together into a large bowl; whisk to combine.
Using an electric hand mixer or a stand mixer, beat butter and sugar until creamy and pale on medium-high speed, about 4 minutes, scraping down the sides and up the bottom of the bowl with a rubber spatula as needed. Once smooth, add sour cream, vanilla extract, and vinegar; mix till well combined.
Turn the mixer to low and add the flour mixture in three batches, alternating with buttermilk, beginning and ending with the flour mixture. Beat in your desired amount of food coloring; mix just until combined.
Divide batter between cake pans. Bake for 25 - 30 minutes on the same shelf, or until a toothpick inserted into the center comes out clean.
Let it rest for 10 minutes in the pan then turn out onto a cooling rack and allow to cool.