Preheat the oven to 375°F and coat a muffin tin with baking spray.

In a large mixing bowl, whisk together the sugar, melted butter, egg, cinnamon, nutmeg, and whole milk until smooth and well combined.

Add the flour and baking powder to the wet mixture.

Whisk gently until the batter is just combined. Do not overmix.

Divide the batter evenly into the prepared muffin tin.

Bake for 18 to 20 minutes, or until the muffins are golden brown and a toothpick inserted into the center comes out clean.

While the muffins bake, stir together the sugar and cinnamon for the topping in one bowl.

Melt the remaining butter and place it in a separate bowl.

Once the muffins are done baking, let them cool in the pan for 10 minutes.

Dip the tops of the muffins into the melted butter.

Immediately dip the buttered tops into the cinnamon sugar mixture until well coated.

Serve warm or let cool completely before storing.