Preheat the oven: Set your oven to 350°F (175°C). Grease and flour two 8-inch or 9-inch round cake pans, then line with parchment paper for easy removal.
Mix the dry ingredients: In a large bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside.
Cream butter and sugar: In another bowl, beat softened butter and sugar together until light and fluffy — about 3–4 minutes using a hand or stand mixer.
Add wet ingredients: Beat in the eggs one at a time. Add vanilla extract and green food coloring, mixing until the color is evenly distributed.
Combine wet and dry: Alternate adding the dry flour mixture and buttermilk to the butter mixture, beginning and ending with the dry ingredients. Mix gently until smooth and well combined.
Add vinegar: Stir in the vinegar just before baking. This activates the baking soda, giving the cake its signature velvety texture.
Bake: Divide the batter evenly between the prepared pans. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean.
Cool: Let the cakes cool in the pans for 10 minutes before transferring to a wire rack to cool completely.
Frost: Once cooled, frost generously with cream cheese frosting for a smooth, tangy finish that complements the cake’s soft sweetness.
