Cream the butter and sugar together until the mixture has a pale colour and is light a fluffy.
One at a time, beat in the eggs and add a tablespoon of flour with each.
Gently fold the remaining flour and the food colouring. You want to get air into the mixture so do not beat it vigorously.
Get out your cupcake baking trays and insert your favorite paper cases.
Transfer equal amounts of the mixture into the cases.
Bake in the center of a fairly hot oven for approximately 20-25 minutes.
Combine the butter and the squash
Gradually stir in the icing sugar
Beat until the icing is fairly thick and creamy. You don't want it too runny or it will run off the sides of the cakes.
Decorate your cakes.
This is a variation of the basic cupcake recipe. This recipe will turn the sponge purple and give you purple / grapefruit icing (flavour and colour). I have used powdered food colouring in this recipe. This is more a personal preference as I find they work better with the mixture and the colours are amazing.
Always remember no matter if you use liquid or powdered colouring, adjust the mixture slightly to compensate e.g. if you more powdered food colouring, reduce the icing sugar ever so slightly. otherwise, you will either end up with icing that it very runny or stiff as a board and hard to apply.