Preheat the oven to 375°F (190°C). Line a standard 12-cup muffin tin with paper liners or lightly grease the muffin cups.
In a large bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, cinnamon, nutmeg, and ginger.
Add the pumpkin puree, eggs, vegetable oil or melted butter, brown sugar, vanilla extract, and milk to the bowl.
Stir the wet and dry ingredients together gently with a spatula until just combined. Do not overmix the batter; a few small lumps are fine.
Fold in the chocolate chips, pecans, or walnuts if using.
Divide the batter evenly between the muffin cups, filling each one about three-quarters full.
Bake for 18–22 minutes, or until the muffin tops are set and a toothpick inserted into the center comes out clean or with a few moist crumbs.
Let the muffins cool in the pan for 5 minutes, then transfer them to a wire rack.
Serve warm or at room temperature with coffee, tea, milk, or butter