Preheat your oven to 350°F (175°C) and prepare your muffin tins by greasing them with butter or lining them with muffin cups.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, salt, ground cinnamon, and nutmeg until well combined.

In a separate bowl, whisk together the egg, milk, vanilla extract, and melted butter until smooth and well combined.

Gently fold the wet mixture into the bowl of dry ingredients, stirring until just moistened.

Spoon the batter into each muffin cup, filling them about two-thirds full, and bake for 20-25 minutes.

Once baked, let the muffins cool in the pan for about 5 minutes, then transfer them to a wire rack.

Prepare the topping by mixing granulated sugar and ground cinnamon in a small bowl while the muffins cool.

Dip each muffin in melted butter, then roll them in the cinnamon sugar mixture until fully coated.