In a mixing bowl, mix butter and sugar with an electric mixer until fluffy.
Combine flour, baking powder, and salt; add to butter mixture alternately with milk, beating at low speed until just combined. Stir in raisins.
Spread batter in a greased 8x8x2-inch baking pan. Sprinkle brown sugar atop. Gradually pour water over sugar.
Bake in a 350 degree F oven about 40 minutes or until a toothpick inserted in the center comes out clean. Serve warm with whipped cream or ice cream. Makes 8 servings.