Cream butter and sugar, add beaten egg, sift flower, baking powder and salt, ad gradually with milk to butter mixture. Fold in mashed banana. Melt butter and sprinkle brown sugar through it on bottom of pan, 8 inches square or small angel food pan. Add well trained crushed pineapple and chopped nuts. Pour batter over this mixture and bake in pre-heated oven of 350 degrees for 20-30 minutes.