1. Cream the butter and the sugar together until light and fluffy.
Beat the eggs in a separate bowl and add to the butter and sugar in 5-6 stages.
Sieve in the flour and cocoa adding the food colouring.
Divide the mixture between 12 muffin tins and bake for 15 minutes at 200°C.
Note: the final result of the cupcakes will depend greatly on the quality of the food colouring. Buy the best quality food colouring you can get (preferablly a gel colour).
For the frosting:
1. Cream the butter in a stand mixer or hand mixer and beat until soft.
2. Add the cream cheese in 2 or three stages followed by the icing sugar again in 2 or 3 stages.
3. Add the lemon juice and beat for a few minutes.
4. Leave to stand in a cool place for at least an hour.
5. Take half of the frosting and add 1/2 tsp red food colour.
6. In a piping bag fitted with a star tube, place the red frosting down one side of the piping bag and half the remaining frosting down the other half of the bag. Pipe swirls on each cupcake.