Heat the oven to 350°. Generously grease a 9×5 inch loaf pan with oil or butter.
Whisk the flour, baking soda, baking powder, cinnamon, salt, nutmeg, and ginger together in a large bowl. Whisk the pumpkin, sugar, melted butter, eggs, and vanilla together in a separate bowl until frothy.
Gently fold the pumpkin mixture into the flour mixture with a rubber spatula until just combined. Fold in the chocolate chips and nuts (if using). The batter will be very thick.
Scrape the batter into the prepared pan and smooth the top. Bake until golden and a toothpick inserted into the center comes out with just a few crumbs attached, 45 to 55 minutes.
Let the loaf cool in the pan for 10 minutes before unmolding onto a wire rack to cool for 1 hour.