*self-rising flour can be used in This recipe; omit salt and Baking soda.
Heat oven to 350 degrees. Mix flour, margarine and powdered sugar. Press in ungreased square pan, 8 X 8 X 2 or 9 X 9 X 2 inches, building up 1/2-inch edges. Bake 20 minutes. Beat remaining ingredients about 3 minutes or until light and fluffy. Pour over hot crust.Bake about 25 minutes or until no indentation remains when touched lightly in center; cool. Sprinkle with powdered sugar if desired. Cut into 1-1/2-inch squares. 25 Squares; 100 Calories Per Square.