Preparation Steps

• Preheat oven to 425°F (220°C). Line a 12-count standard muffin pan with liners or spray very well with non-stick cooking spray.
• In a large bowl, whisk together the flour, cinnamon, nutmeg, baking powder, baking soda, and salt. Set aside.
• In a separate large bowl, beat the softened butter with an electric mixer until soft and fluffy. Scrape down the sides of the bowl.
• Add the brown sugar and granulated sugar to the butter and beat on medium-high speed for about 3 minutes. Scrape down the sides of the bowl.
• Add the eggs and beat for 30 seconds.
• Add the sour cream, milk, and vanilla extract. Beat to combine.
• Add the dry ingredients to the wet ingredients and stir with a rubber spatula until just combined. Do not overmix.
• Evenly divide the batter between the muffin pan cavities, filling each about 2/3 to 3/4 full. The batter will be thick.
• Bake for 5 minutes at 425°F (220°C).
• Without opening the oven, reduce the temperature to 350°F (175°C) and bake for another 15 minutes, or until a toothpick inserted into the center comes out clean.
• Let the muffins cool in the pan for about 5 minutes, then transfer them to a wire rack to cool further.
• While the muffins are cooling, melt the butter in a small bowl.
• In a separate bowl, combine the granulated sugar and cinnamon for the coating.
• If using liners, unwrap the muffins. Brush each muffin with melted butter, then roll it in the cinnamon-sugar mixture. Repeat for all muffins.
• Using a piping bag with a round tip filled with dulce de leche, carefully insert the tip into the center of each muffin and squirt a small amount of filling.
• Optional: Drizzle more dulce de leche over the tops of the muffins before serving. Serve warm.