Preheat and prep: Heat the oven to 375°F (190°C). Line a 12-cup muffin tin with liners or lightly grease.
Whisk wet ingredients: In a large bowl, whisk pumpkin, eggs, oil, brown sugar, granulated sugar, and vanilla until smooth.
Add dry ingredients: Sprinkle flour, baking soda, baking powder, spices, and salt over the wet mixture.
Stir gently with a spatula until just combined. Do not overmix.
Fold in extras: If using chocolate chips, nuts, or cranberries, fold them in now.
Portion the batter: Divide evenly among muffin cups, filling each about 3/4 full. Top with coarse sugar or pumpkin seeds if you like.
Bake: Bake 16–20 minutes, or until the tops spring back and a toothpick comes out clean or with a few moist crumbs.
Cool: Let muffins rest in the pan 5 minutes, then transfer to a rack. Enjoy warm or at room temperature.