Preheat oven to 180 degrees C. Grease and flour a 23cm round pan.
In a medium bowl cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time then stir in the vanilla. Combine the flour, baking powder and salt; stir into the batter alternately with the milk. If the batter is too stiff a tablespoon or two of milk may be added. Spread the batter evenly into the prepared pan.
Bake for 30 to 35 minutes in the preheated oven until a toothpick inserted into the centre comes out clean. Cool in pan on a wire rack then turn out onto a serving plate. Dust with icing sugar right before serving.