Prepare the cake batter

1. Preheat the oven to 175°C (350°F) and grease and line three 15 cm (6-inch) cake pans.
2. In a large bowl, cream the butter, oil, and sugar until smooth.
3. Add the eggs one at a time, mixing well after each addition, then add the vanilla and red gel food coloring.
4. In a separate bowl, mix the cake flour, cocoa powder, baking powder, baking soda, and salt.
5. Mix the buttermilk with the vinegar.
6. Add the dry ingredients and the buttermilk alternately to the batter, starting and ending with the dry ingredients, mixing just until combined.
7. Divide the batter evenly between the three pans and smooth the tops.
8. Bake for 22–25 minutes, until a toothpick inserted in the center comes out clean.
9. Let the cakes cool completely before unmolding.

Prepare the cream cheese frosting

1. Beat the butter and powdered sugar until smooth and creamy.
2. Add the cold cream cheese and vanilla, then mix just until smooth.
3. Stop mixing as soon as the frosting is combined.

Assemble the cake

1. Level the cake layers if needed.
2. Spread frosting between each layer.
3. Apply a thin crumb coat over the whole cake and refrigerate for 20 minutes.
4. Cover the cake with the remaining frosting and decorate with cake crumbs if desired.