Preheat your oven to 350°F (175°C). Prepare a 12-cup muffin pan with nonstick spray or parchment paper.

In a large mixing bowl, whisk together the flour, sugar, baking powder, cinnamon, and salt until evenly mixed.

In another bowl, whisk together the milk, egg, melted butter, and vanilla extract until smooth.

Pour the wet ingredients into the dry ingredients and gently stir until just combined.

Divide the batter among the muffin cups, filling each about three-quarters full.

Bake for 18-22 minutes until golden brown and a toothpick comes out clean.

Let the muffins cool on a wire rack for about 10-15 minutes.

While muffins cool, melt some butter and mix sugar with cinnamon in a bowl.

Dip the tops of the muffins in melted butter, then roll in the cinnamon sugar mixture.

Transfer to a cooling rack and let them cool to room temperature or serve warm.