Cream the butter, add sugar gradually, and egg well beaten. Mix and sift flour, baking powder, and salt, adding alternately with milk to first mixture. Beat thoroughly, and bake in a buttered round tin. Cool, spread thickly with sweetened fruit, and cover with Cream Sauce I. or II. Fresh strawberries, peaches, apricots, raspberries, or canned quince or pineapple may be used. When canned goods are used, drain fruit from syrup and cut in pieces. Dilute cream for Cream Sauce with fruit syrup in place of milk.