Preheat your oven to 375°F (190°C).

Lightly grease a standard 12-cup muffin pan with butter or nonstick baking spray. You can also line the muffin cups with paper liners for easier cleanup.

If greasing the pan with butter, lightly dust the cups with flour and shake out any excess.

In a medium mixing bowl, whisk together the all-purpose flour, baking powder, kosher salt, and ground cinnamon.

Make sure the cinnamon and baking powder are evenly distributed throughout the flour.

Set the bowl aside while you prepare the remaining ingredients.

Wash, core, and dice the fresh apples into small, evenly sized pieces.

In a separate bowl, combine the additional 2 teaspoons of flour with ½ teaspoon of ground cinnamon.

Add the diced apples and toss until lightly coated.

This simple step helps distribute the apples throughout the muffin batter instead of allowing them to collect at the bottom.

Place the softened butter and granulated sugar in a large mixing bowl.

Using an electric mixer, beat them together for approximately 3 minutes, until the mixture becomes lighter in color and fluffy.

Add the eggs one at a time, mixing well after each addition.

Pour in the alcohol-free vanilla extract and mix until combined.

Add approximately one-third of the flour mixture to the butter mixture.

Mix gently, then add half of the milk.

Continue alternating the remaining flour mixture and milk, finishing with the flour.

Stir only until the ingredients are combined.

Avoid overmixing, as this can create dense muffins instead of a soft, tender texture.

Add the cinnamon-coated apple pieces to the batter.

Using a spatula, gently fold them in until evenly distributed.

The batter should be thick but scoopable, with small apple pieces throughout.

Divide the batter evenly among the prepared muffin cups.

Fill each cup approximately two-thirds to three-quarters full.

Leave enough room for the muffins to rise during baking.

Place the muffin pan on the center rack of the preheated oven.

Bake for approximately 20–30 minutes, or until the tops are lightly golden and a toothpick inserted into the center comes out clean or with a few moist crumbs.

If the toothpick has wet batter attached, continue baking for another 2–3 minutes before checking again.

While the Cinnamon Apple Muffins are baking, melt the butter for the topping.

Allow it to cool slightly, then transfer it to a shallow bowl.

In another bowl, mix the granulated sugar with 1–2 tablespoons of ground cinnamon.

Stir until evenly combined.

Remove the baked muffins from the oven and let them cool in the pan for approximately 5 minutes.

Carefully transfer them to a wire rack.

While the muffins are still warm, brush their tops with melted butter or gently dip the tops into the butter.

Immediately dip the buttered tops into the cinnamon sugar mixture.

Allow the muffins to cool slightly before serving.