Preheat the oven to 180 C / Gas 4. Line a 12 hole muffin tin with paper cases.
In a bowl, beat together the butter and sugar until light and fluffy. Add the eggs, one at a time, beating well after each addition until pale and creamy. Fold in the flour, vanilla extract and milk gradually until well integrated. Divide the mixture between the prepared paper cases (about 2 tablespoons per paper case), taking care not to overfill to ensure a good rise.
Bake in the preheated oven for 20 minutes until risen, golden brown and a skewer inserted into the centre comes out clean. Remove from the oven and allow to cool on a cooling rack. Allow to cool completely if decorating.