Heat oven to 350 degrees. Spray pie plate, 10x1 1/2 inches, with cooking spray. Place canned pumpkin, evaporated milk, egg whites, sugar, flour, pumpkin pie spice, baking powder, salt and grated orange peel in blender or food processor in order listed. Cover and blend on medium speed until smooth. Pour into pie plate. Sprinkle with topping. Bake 50-55 minutes or until knife inserted in center comes out clean. Cool 15 minutes. Refrigerate about 4 hours or until chilled.
Brown Sugar Topping: Mix brown sugar, oats and butter.