COMBINE flour, cocoa, baking soda and salt in small bowl. Heat 1 1/4 cups sugar, morsels, applesauce and margarine in large, heavy-duty saucepan over low heat, stirring constantly just until morsels are melted. Remove from heat. Stir in egg whites.
ADD cocoa mixture and vanilla extract; stir well. Spread into greased 13 x 9-inch baking pan. Stir together cream cheese, 1 tablespoon sugar and milk in small bowl. Drop by rounded teaspoon over batter; swirl over surface of batter with back of spoon.
BAKE in preheated 325° F oven for 22 to 28 minutes or just until set. Cool completely in pan on wire rack.