Crust: preheat oven to 350 degrees. Cream butter and powdered sugar. Stir in flour. Pat mixture into 12-inch pizza pan. Prick bottom with fork. Bake 10 minutes or until edges are brown and cool.
Filling: Combine cornstarch, sugar and mace. Stir in orange juice and jelly and cook, stirring, until mixture boils and is thick. Cool. Arrange peach slices on crust and spoon sauce over peaches. Refrigerate until glaze is set. Serve with whipped cream.