01 - Preheat oven to 350°F. Grease and line two 9-inch round cake pans with parchment paper.
02 - Whisk together flour, cocoa powder, baking soda, and salt in a medium bowl. Set aside.
03 - Beat sugar and oil in a large bowl until combined. Add eggs one at a time, mixing well after each addition.
04 - Stir in buttermilk, vanilla extract, vinegar, and green food coloring. Whisk until mixture is evenly colored.
05 - Add dry ingredients to wet ingredients in two batches, mixing just until incorporated.
06 - Divide batter evenly between prepared pans. Bake for 28–32 minutes or until toothpick inserted in center comes out clean.
07 - Cool cakes in pans for 10 minutes, then turn out onto wire racks to cool completely.
08 - Beat cream cheese and butter until smooth and fluffy. Add powdered sugar, vanilla, and salt; beat until light and creamy.
09 - Place one cake layer on serving plate. Spread frosting over top. Add second layer and frost entire cake. Decorate with green sprinkles or cake crumbs if desired.