1. Preheat the oven to 350°F (175°C) and line a 12-cup muffin tin with liners or lightly spray.

2. In a large bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, and nutmeg.

3. In another bowl, whisk pumpkin puree, brown sugar, eggs, melted butter or oil, milk or buttermilk, and vanilla extract until smooth.

4. Pour the wet ingredients into the dry ingredients and fold gently with a spatula until just combined.

5. Scoop the batter into the muffin cups, filling each about two thirds full.

6. Bake for 20 minutes or until a toothpick inserted in the center comes out clean.

7. Let the muffins cool in the pan for five minutes, then transfer to a cooling rack.

8. In a small bowl, mix granulated sugar and ground cinnamon for the topping.

9. Brush the warm muffin tops with melted butter and immediately sprinkle or dip them in the cinnamon sugar mixture.

10. Serve warm or at room temperature with coffee or cider.