01 -  Preheat oven to 375°F. Line a 12-cup muffin tin with paper liners or lightly grease each cavity. 
 02 -  In a large mixing bowl, whisk the pumpkin purée, granulated sugar, brown sugar, eggs, oil, sourdough starter, and vanilla extract until fully smooth. 
 03 -  In a separate bowl, combine the all-purpose flour, baking soda, baking powder, salt, cinnamon, nutmeg, cloves, and ginger and whisk thoroughly. 
 04 -  Add the dry mixture into the wet ingredients and gently fold together using a spatula until no dry streaks remain. Avoid overmixing to maintain tenderness. 
 05 -  Fold in the chocolate chips until evenly dispersed throughout the batter. 
 06 -  Divide the batter evenly among the prepared muffin cups, filling each approximately three-quarters full. 
 07 -  Bake for 20 to 22 minutes, or until a toothpick inserted into the center of a muffin emerges clean or with just a few moist crumbs. 
 08 -  Allow muffins to cool in the tin for 5 minutes before transferring to a wire rack to cool fully.