Preheat the oven to 350 F (180C). Line standard muffin tins with paper liners.
If you are using milk and vinegar instead of buttermilk, mix these 2 ingredients and set aside.
In a large bowl whisk together cake flour, cocoa and salt.
In another bowl combine sugar, oil, egg, vanilla, food coloring and buttermilk (or milk and vinegar mixture). Mix it all with an electric mixer on medium-high speed.
Combine wet and dry ingredients and mix them very well.
Pour batter in lined cups, filling each three-quarters full. Bake until a cake tester inserted in centers comes out clean, about 20 minutes.
Remove from the oven and let it cool before removing cupackes from the pan.
Frosting
Pour heavy cream into a bowl and whisk on high speed until it reaches a whipped cream texture. Add cream cheese, sugar and vanilla and whisk on high speed for about 30 seconds.