Combine first three ingredients; set aside. Mash rice in a bowl with a potato masher. Add egg and egg whites, stirring with a whisk until well blended. Add flour mixture and milk alternately to rice mixture, beginning and ending with flour mixture, stirring with a whisk after each addition.

Heat muffin pans at 450 F for 3 minutes; coat with cooking spray. Divide batter among pans.

Bake at 450 F for 15 minutes; then reduce the heat to 350 F and bake 20 minutes longer. Coo1 in pan 3 minutes. Yield: 12 popovers (about 70 calories each).