Preheat the oven to 350°F. Grease a 9×5-inch loaf pan and line it with parchment paper, leaving an overhang for easy removal.

In a large bowl, whisk together the all-purpose flour, baking soda, baking powder, ground cinnamon, ground nutmeg, ground cloves, ground ginger, and kosher salt until evenly combined.

In another bowl, whisk together the pumpkin purée, large eggs, granulated sugar, light brown sugar, vegetable oil, sour cream, and vanilla extract until smooth.

Pour the wet ingredients into the dry ingredients. Fold gently with a spatula until no dry streaks remain, then transfer the batter to the prepared loaf pan and smooth the top.

Sprinkle pumpkin seeds and coarse sugar over the top if using.

Bake at 350°F for 55–65 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs. If the top browns too quickly, loosely cover with foil during the last 15 minutes.

Cool the bread in the pan for 15 minutes, then transfer to a wire rack and cool completely before slicing. Serve plain or with butter, cream cheese, or maple butter.