Preheat oven to 400 degrees. In a medium bowl, mix flour, sugar, baking powder, salt, and nutmeg with a wire whisk. Combine milk, egg and 1/3 cup melted butter in a small bowl. Pour wet ingredients into dry ingredients and mix well.
Grease muffin tins or use paper liners and fill about two-thirds full. Bake 20 minutes. Brush remaining melted butter over the tops, then sprinkle on the cinnamon mix.