Preheat the oven to 180 C / Gas 4 and line a 12-hole muffin tin with paper cases.
Cream the butter and sugar together in a bowl until pale. Beat in the eggs a little at a time and stir in the vanilla extract.
Fold in the flour using a large metal spoon, adding a little milk until the mixture is of a dropping consistency. Spoon the mixture into the paper cases until they are half full.
Bake in the oven for 10 to 15 minutes, or until golden on top. Insert a skewer into the top of one of the cupcakes, if it comes out clean then they are done. Set aside to cool for 10 minutes, then remove from the tin and cool on a wire rack.