Preheat your oven to 350°F (175°C) and grease your muffin tin or line with paper liners.

In a large mixing bowl, whisk together the flour, sugar, baking powder, cinnamon, and salt until well combined.

In another bowl, beat the egg and add the milk, melted butter, and vanilla extract. Mix until well blended.

Pour the wet mixture into the dry ingredients and gently fold until just combined; it’s okay if there are a few lumps.

Fold in the chopped apples carefully to avoid breaking them down too much.

Using a spoon or cookie scoop, fill each muffin cup about ¾ full with the batter.

Place in the preheated oven and bake for 18-20 minutes or until a toothpick inserted in the center comes out clean.

For optional topping, combine sugar and cinnamon in a small bowl. Once muffins cool slightly, roll each in the cinnamon-sugar topping.

Let the muffins cool in the pan for a few minutes before transferring to a wire rack. Enjoy warm or at room temperature.