Heat the oven: Preheat to 350°F (175°C). Line a 12-cup muffin tin with paper liners or grease well.
Whisk dry ingredients: In a large bowl, whisk the gluten free flour, baking powder, baking soda, salt, cinnamon, ginger, nutmeg, and cloves.
Mix wet ingredients: Add brown sugar, eggs, pumpkin puree, oil, milk, and vanilla to the bowl.
Whisk until smooth and combined. Do not overmix.
Add mix-ins: If using chocolate chips or nuts, fold them in gently with a spatula.
Fill the pan: Divide batter evenly among the cups, about 3/4 full. Sprinkle tops with coarse sugar if you like a slight crunch.
Bake: Bake for 18–22 minutes, until the tops spring back and a toothpick comes out clean or with a few moist crumbs.
Cool: Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
This helps set the structure.