Preheat oven to 350 degrees F. Line 8.5 x 4.5 inch loaf pan with parchment paper, butter, then flour, respectively
Cream butter and sugars until one cohesive mixture
Add eggs, one at a time, until fully incorporated
Whip the mixture until light and airy
Meanwhile, combine dry ingredients in a seperate bowl
Combine pumpkin puree, sourdough starter, and vanilla in another small bowl
While mixing the butter mixture, alternate between adding the dry and wet mixtures until everything is just incorporated
Pour batter into an 8.5 x 4 inch loaf pan that is lined with parchment paper
Cover and rest/rise the dough for a few hours. You can bake immediately if you like, but resting the dough will allow it to ferment and the flavors to develop!
Sprinkle the pumpkin seeds in one layer on top of the dough
Bake for 1 hour and 15 minutes or until a toothpick comes out clean
Let bread completely cool in the pan on a wire rack