Preheat your oven to 180°C (350°F/Gas 4). In a large bowl, thoroughly beat together the butter and sugar. Add the eggs one at a time, beating well after each one goes in. Add the vanilla and then sift in the flour and baking powder. Beat well, adding the milk a little at a time. You should have a thick and creamy batter.
Spoon heaped teaspoons of batter into small paper cupcake cases. Don’t put in too much batter or the cakes will puff up too much, and these look lovely when the icing is flush with the top of the cases.
Put the filled paper cases on baking trays and bake in batches for 15 minutes or so, until they are golden on top. Cool completely before icing.
For the icing, put the icing sugar in a bowl, add a few drops of food colouring and gradually stir in 3 tablespoons of cold water until you have a smooth but thick icing that is stiff enough to cling to the cakes. Add more colouring if you think you’d like it brighter. Working a few at a time, drop about a teaspoon of icing on top of each cake and spread it gently with the back of the spoon so that it covers the top. If the icing gets too thick as you are working, add a few more drops of water. Sprinkle on any decorations before the icing dries.
Once the icing has dried, the cakes can be stored in a biscuit tin for 5–6 days.