Preheat the oven to 180 C / Gas 4. Grease and line a 18cm (7 in) round cake tin.
Cream together the butter and sugar until light and fluffy.
Beat in the eggs a little at a time, so the mixture doesn't curdle.
Sift the flour and baking powder together and fold lightly into the mixture. Add a little milk if necessary to give a soft dropping consistency. Place in prepared tin.
Bake for 30 to 45 minutes, or till a skewer inserted in the centre comes out clean.