Preheat your oven to 375°F (190°C) and prepare a muffin pan by greasing it lightly or lining it with paper liners.

In a large mixing bowl, whisk together the all-purpose flour, baking powder, sugar, salt, and chopped rosemary until well combined.

Add the grated sharp cheddar cheese to your dry ingredients and gently mix until the cheese is coated with the flour mixture.

In a separate bowl, whisk together the egg, milk, and melted butter until smooth. Fold in the chopped apples.

Create a well in the center of your dry ingredients and pour in the apple mixture. Gently stir until just combined.

Evenly distribute the batter into the prepared muffin cups, filling each about three-quarters full.

Bake for 30 minutes until a toothpick inserted in the center comes out clean and the tops are golden brown.

Let the muffins cool in the pan for about 5 minutes, then transfer to a wire rack to cool completely.