Preheat oven to 170C (150 fan). Grease and line two 9-inch cake tins (or one high-sided tin – if doing this, reduce temp by 10C)
Sift the flour, baking powder and cocoa powder in one bowl and mix them to combine.
In a different bowl, beat the butter until creamy. Add all the sugar and beat together until white and fluffy. Add two eggs and vanilla, and beat until they are well combined. Add half the buttermilk, the food colouring and half the flour to the bowl, and mix slowly to just combine. Add the other half of the dry mix and the rest of the buttermilk. Mix very slowly until you’ve got a lovely red colour. Pour the mix into your tins and get it straight in the oven.
If you’re baking it as one cake, it will take 40-50 minutes. But if you’re baking it as two thinner ones, it will take 25-30 minutes. Test by poking a knife in and seeing if it comes out clean. Whilst the cake cools, make the cream cheese icing. Beat the butter and icing sugar until it is a consistent mixture. Add all the cream cheese and beat until smooth (a food processor helps here). Spread the cooled cake with icing and plop the other layer on top (or cut the single cake in half and spread between layers).
Then, cover the whole cake with icing and set aside. Roll out nearly all the fondant and cover the cake with it, trimming any excess. Combine the excess and any leftover with red food colouring to make red icing. Use this to cover with little red roses.