In a large mixing bowl, combine sugar, oil, eggs and pumpkin puree.
Mix in the sourdough starter.
Add the white flour, whole wheat flour, cinnamon, cloves, nutmeg and water. Mix until smooth.
Cover the batter with plastic wrap or a damp tea towel and leave somewhere warm for 6-8 hours. If you are not ready to bake straight away, store the fermented batter in the fridge for up to 24 hours.
When the fermenting time is up, preheat your oven to 180C/350F.
Uncover the batter and sprinkle baking soda, baking powder and salt on top. Mix it in until combined. Don't overmix.
Grease or line your muffin cups and fill 2/3 full with the batter.
Bake the muffins for about 10 minutes until risen and golden. Remove from the muffin pan and let them cool on a cookie rack.