01 - Preheat oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners or lightly grease each well.
02 - In a large bowl, whisk pumpkin purée, granulated sugar, brown sugar, eggs, oil, sourdough starter, and vanilla extract until the mixture is smooth and homogeneous.
03 - In a separate bowl, whisk together flour, baking soda, baking powder, salt, cinnamon, nutmeg, cloves, and ginger until evenly mixed.
04 - Add dry mixture to wet ingredients and fold gently with a spatula until just combined. Avoid overmixing to ensure tender muffins.
05 - Fold in dark chocolate chips, distributing them evenly throughout the batter.
06 - Divide batter evenly among the prepared muffin cups, filling each approximately three-quarters full.
07 - Bake for 20 to 22 minutes until a toothpick inserted into the center emerges clean or with a few moist crumbs.
08 - Allow muffins to cool in the tin for 5 minutes. Transfer them to a wire rack to cool completely before serving.