In bowl, beat egg with juice, oil and vanilla. Stir in flour, sugars, baking powder, and salt just until flour is moistened. (will be lumpy) Stir in nuts and apple. Fill prepared muffin tins. (greased or paper lined.) Sprinkle with cinnamon sugar. Bake at 400 F for 20 minutes or until golden brown. From Domino Back of the Box.