Preheat oven and prep pans: Preheat oven to 350°F, then grease and flour two 9-inch round cake pans until coated evenly to prevent sticking.

Mix dry ingredients: In a large bowl whisk flour, cocoa, baking soda, and salt until evenly combined and no lumps remain.

Blend wet ingredients: In another bowl whisk buttermilk, oil, eggs, vanilla, and red food coloring until smooth, then stir in vinegar.

Combine batters: Pour wet mixture into dry ingredients, then gently fold until the batter is smooth and uniformly red.

Bake the cakes: Divide batter evenly between pans and bake at 350°F for 25–30 minutes, or until a toothpick comes out clean.

Cool layers: Let cakes rest in pans for 10 minutes, then turn onto wire racks to cool completely.

Beat cream cheese & butter: In a chilled bowl, whip cream cheese and softened butter at medium speed until light and fluffy.

Add sugar and vanilla: Gradually blend in powdered sugar and vanilla extract until the frosting is thick and creamy.

Place one cake layer on a serving plate, spread a third of the frosting evenly, top with second layer, then frost top and sides.

Chill before serving: Refrigerate cake for at least 1 hour to set the frosting and let flavors meld.