PREHEAT oven to 350°F. Beat eggs lightly in medium bowl with wire whisk. Add granulated sugar and margarine; mix well. Stir in graham crumbs, apple and walnuts until well blended.
SPREAD evenly into greased 8-inch square baking pan.
BAKE 40 to 45 minutes or until firm to the touch. Cool completely. Cut into 16 squares to serve. Sprinkle with powdered sugar just before serving.