In large bowl, combine the flour, sugar, baking powder, cinnamon, salt and nutmeg. In a small bowl, whisk the egg, milk and oil. Stir into dry ingredients just until moistened. Fold in apples. In another small bowl, combine topping ingredients; set aside 3 tablespoons topping.
Spoon half of the batter into 12 greased muffin cups. Sprinkle with the remaining topping. Cover with enough batter to fill muffin cups two-thirds full. Sprinkle with reserved topping.
Bake at 400° for 20-25 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pan to a wire rack.