Preheat oven to 350°F. Lightly grease a 9 × 5-inch loaf pan with butter or line it with parchment paper.
In a large mixing bowl, beat the melted butter, brown sugar, and granulated sugar with a handheld or stand mixer for 3–5 minutes, until well combined and slightly lighter in texture.
½ cup melted butter, 1 cup brown sugar, ¼ cup granulated white sugar
Add the eggs, vanilla extract, pumpkin puree, and sourdough discard. Mix for 3 minutes, until well combined.
1½ cups pumpkin puree, 2 large eggs, ½ cup sourdough discard, 1 teaspoon vanilla extract
In a separate bowl, whisk together the flour, baking soda, baking powder, salt, and pumpkin pie spice.
2 cups all-purpose flour, 1 teaspoon baking soda, 2 teaspoons baking powder, 1 teaspoon salt, 2½ teaspoons pumpkin pie spice
Gently fold the dry ingredients into the wet ingredients until just incorporated. Do not overmix.
Fold in the chocolate morsels until evenly distributed.
½ cup chocolate morsels
Pour the batter into the prepared loaf pan. This batter rises quite a bit, so avoid overfilling the pan. I leave a little batter in the mixing bowl rather than scraping every last bit into the pan.
Bake for approximately 60 minutes, checking for doneness at 55 minutes. Insert a toothpick into the center. If it comes out clean or with a few moist crumbs, the bread is done. If the center is still wet, bake for another 5 minutes or as needed.
Allow the bread to cool in the pan for about 1 hour before removing and slicing. Cooling helps the loaf set so the slices hold together better.
