Tea-party cup cakes

This is a great recipe of party cup cakes, I found this one in one of Jamie Oliver's cookbooks. My kids love them! 

Makes 18

Ingredients for the cake mix:
225g unsalted butter, softened
225g self-raising flour
225g caster sugar
4 large free-range eggs
Zest of 1 lemon
Icing:
Icing sugar
A bit of water or lemon juice
Food colouring
Cocoa powder

Method:
Preheat your oven to 190C/350F/gas4. Place 18 paper cases into your muffin tins.
Beat the butter and sugar together until very light and fluffy. Add the eggs, one at a time, beating each one well before you add the next, then fold in the flour and lemon zest. Evenly spoon your mixture into your paper cases. Put the muffin tins into the oven and bake for 15 minutes or until ready. You can check if the muffins are cooked by sticking a wooden skewer into one of them. When you take it out, it should come out dry.
When they are cooked, remove them from the oven and let the cakes cool down.

Now, it's time for the fun part! Making icing!
Here you can do anything you like.
I have made a simple icing out of icing sugar and water, combining it with a different food colourings or cocoa powder, or lemon juice.
But you can also make fresh fruit icing, for example, by mixing fresh or frozen berries with icing sugar.
You can make only one type of icing or lots of different ones, you can also decorate them as desired.
Experiment the way you like!