Preheat your oven to 350°F (175°C) and grease the loaf pan or line it with parchment paper for easy removal.
In a large mixing bowl, whisk together the sourdough starter, pumpkin puree, granulated sugar, brown sugar, and vegetable oil until well combined.
Add the eggs one at a time, mixing well after each addition until the mixture is smooth.
In a separate bowl, sift together the flour, baking soda, baking powder, cinnamon, nutmeg, ginger, and salt.
Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined. Be careful not to overmix.
If desired, fold in the chopped nuts or seeds.
Pour the batter into the prepared loaf pan, smoothing the top with a spatula.
Bake in the preheated oven for 55 to 60 minutes, or until a toothpick inserted into the center comes out clean.
Once done, remove from the oven and let it cool in the pan for 10 minutes. Then, transfer it to a wire rack to cool completely before slicing.