mix the butter and white sugar until creamy. combine the flour, baking powder and salt. add this to the butter mixture. add the milk. mix well. this will be very thick. spread into a 8inch square pan that has been greased. mix the brown sugar and the water with a whisk. pour over the batter. do not stir. bake app 40 min at 350 until golden. mixture will be thin but will thicken as it cools. serve cold or at room temp. whip cream or ice cream sprinkled with heath bars makes it pretty but not necessary.