Chocolate cola cake with chocolate cola glaze and a vanilla buttercream.
Preheat your oven to 350 degrees F. Prepare three 8-inch or four 6-inch round baking pans by spraying each pan with nonstick spray, lining the bottom with parchment paper and spraying again. Set aside.
In a bowl of a stand mixer fitted with a paddle attachment, combine the flour, cocoa powder, baking powder, and salt. Stir to combine well. Set aside.
Once your eggs are full incorporated, add the buttermilk and vanilla to the wet ingredients and stir well.
Using a kitchen scale, divide batter evenly among your pans (about 18 to 20 ounces of batter in each of the 8-inch pans, 15 ounces in each of the 6-inch pans), spreading evenly with a small offset palette knife.
Bake for about 23 to 25 minutes. Check cake at 20 minutes and then set the timer for 2 to 3 minute intervals if the cake needs to bake longer. You're looking for a few moist crumbs to come out on the toothpick when inserted into the center of the cake.
Note: To make the ombre effect on the cake, take about 1 1/2 cups of the buttercream and combine with about 3 tablespoons of the glaze.