Cut Crusts Off The Bread Slices. Cut Into 1" Squares In A Sauce Pan Combine Cheeses And Butter. Heat Over Low Heat Until Melted. Stir To Mix Thoroughly. Beat Egg Whites Until Stiff. Slowly Pour Cheese Mixture Into Beaten Egg Whites And Fold Gently. Dip Bread Cubes In Cheese Mixture And Coat Well. Place On Lightly Greased Baking Sheet. Refrigerate 1 Hour Or Freeze 15 Minutes. Preheat Oven To 350 Deg F. Bake For 15 Minutes Or Until Light Golden Brown. Makes 54 Melts.