Preheat your oven to 350°F (175°C). Prepare a muffin pan by spraying the cups lightly with nonstick cooking spray.

In a medium to large mixing bowl, sift together the flour, baking powder, salt, and nutmeg to ensure even distribution.

In a separate bowl, whisk together the milk, melted butter, sugar, and egg until just combined.

Pour the wet mixture into the dry ingredients and stir gently until just blended. The batter should remain slightly lumpy; take care not to overwork it to preserve a tender crumb.

Use an ice cream scoop or spoon to divide the batter evenly among the muffin cups. This quantity yields approximately 8 larger muffins or up to 12 smaller ones, depending on how much batter is used per cup.

Place the muffin tin in the preheated oven and bake for 20 to 25 minutes, or until the edges are lightly golden and a toothpick inserted into the center comes out clean.

While the muffins are baking, prepare the topping by combining the sugar and cinnamon in a shallow dish. Pour the melted butter into a separate bowl.

Once baked, allow the muffins to cool slightly before handling. While still warm, dip each muffin top—or the entire muffin, for enhanced flavor—into the melted butter, then immediately roll in the cinnamon-sugar mixture to coat thoroughly.