1. Start by preheating your oven to 350°F. Grab two 12-count mini muffin pans and spray them with floured cooking spray to prevent sticking.
2. In a large mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, add the egg, butter, granulated sugar, brown sugar, and vanilla. Beat the mixture on medium-high speed until it becomes light and fluffy – this should take about 3 minutes.
3. Stop the mixer and scrape down the sides of the bowl. Add the buttermilk and beat until just combined.
4. Add the flour, cinnamon, baking powder, ground nutmeg, and optional pinch of salt. Mix on low speed until just incorporated.
5. Using a spoon sprayed with cooking spray, drop rounded tablespoons of batter into the prepared muffin pans, filling each cavity about three-quarters full.
6. Place the muffins in the oven and bake for about 9 to 11 minutes, or until the tops are domed and a toothpick comes out clean.
7. Allow the muffins to cool in the pans for about 10 minutes. Meanwhile, prepare the coating.
8. In a small bowl, melt the butter. In another bowl, stir together the granulated sugar and cinnamon.
9. Dip each muffin top into the melted butter, then into the cinnamon-sugar mixture. Repeat until all muffins are coated.
10. Serve immediately or store in an airtight container for up to 4 days.
