Cream together the butter or margarine
and sugar until light and fluffy. Gradually add the eggs and vanilla
essence, beating well after each addition. Fold in the flour, baking
powder and salt alternately with the milk, beating well. Spoon the
mixture into paper cake cases (cupcake papers) and bake in a preheated
oven at 190°C/375°F/gas mark 5 for 20 minutes until a skewer inserted
in the centre comes out clean.