Preheat oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners or lightly grease the cups. This temperature gives good rise without over-browning.
In a medium bowl, whisk together flour, baking soda, baking powder, salt, cinnamon, nutmeg, and ginger until evenly combined. This prevents pockets of leavener or spice.
In a large bowl, whisk pumpkin puree, granulated sugar, brown sugar, oil, eggs, and vanilla until smooth and uniform in color. The mixture should look glossy and pourable.
Add the dry ingredients to the wet ingredients. Stir with a spatula just until no dry flour remains. The batter will be thick. Fold in the chocolate chips gently. Overmixing develops gluten and leads to dense muffins.
Divide batter evenly among the 12 muffin cups, filling each about ¾ full. Sprinkle with coarse sugar if using. Bake 18–22 minutes, until the tops are golden, spring back when lightly pressed, and a toothpick inserted in the center comes out with a few moist crumbs (not wet batter).
Let muffins cool in the pan for 5 minutes, then transfer to a wire rack. This prevents soggy bottoms while keeping the centers soft.