Preheat Oven & Prep Pan:
Preheat oven to 375°F (190°C). Line a muffin tin with paper liners or lightly grease it with non-stick spray.
Mix Dry Ingredients:
In a large bowl, whisk together flour, both sugars, baking powder, baking soda, salt, cinnamon, and nutmeg.
Mix Wet Ingredients:
In a medium bowl, whisk together eggs, melted butter, milk, and vanilla extract.
Combine:
Pour the wet ingredients into the dry ingredients and stir until just combined—do not overmix. Fold in the chopped apples.
Fill Muffin Cups:
Divide batter evenly among muffin cups, filling each about 3/4 full.
Add Topping:
In a small bowl, mix the sugar and cinnamon. Sprinkle generously over the tops of each muffin.
Bake:
Bake for 18–22 minutes, or until a toothpick inserted into the center comes out clean.
Cool:
Let muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.