Preheat the oven to 400F/200C. Prepare the parchment paper for your tins or butter them well so that your muffins do not stick to the walls. Do the same for the baking sheet if using one.
Mix the eggs, sourdough discard, sugar, pumpkin puree, vegetable oil, and vanilla in a bowl. Break up all the lumps and combine well. At this point don’t worry about overmixing your batter yet.
Add flour, baking soda, baking powder, cinnamon, salt, and chocolate chip.
Now since the baking soda and powder came into contact with liquid ingredients, you want to mix as little as possible and get your muffins to the oven as soon as you can not to lose any of those precious CO2 bubbles that will give your sourdough chocolate chip pumpkin muffins a beautiful rise.
Scoop the batter into the muffin tin. Fill them up to the top (¾ is ok too!) for a higher rise. Pour the remaining batter onto a baking sheet.
Place the tins into the oven and bake on 400F/200C for 5 minutes, then lower the heat to 350F/175C and bake for another 15 minutes. Check for doneness with a toothpick or a fork. If they come out clean then your muffins are ready, if not, leave in for another 5 minutes and check again.
Take the muffins out from the oven and let them cool for about 15 minutes. Cut up the dough on the baking sheet and place it on a plate. Sprinkle with some powdered sugar for presentation and extra sweetness! Your sourdough chocolate chip pumpkin muffins and bars are ready, enjoy!