Preheat oven to 350.

Grease a 6-cup large muffin pan or 12-cup regular size muffin pan (or line with muffin cups).

Combine egg, egg white, milk, and butter in a large bowl and whisk thoroughly.

Add flour, baking powder, and salt, and stir with a spoon until moistened.

Add cheddar and apple and stir gently.

Divide batter among prepared cups.

Bake large muffins for 22-26 minutes and regular sized muffins for 16-20 minutes.

Check for doneness with a toothpick or cake tester.