In a large bowl, whisk together the active sourdough starter, pumpkin puree, granulated sugar, brown sugar, melted butter, eggs, and vanilla extract until well combined.
In a separate bowl, whisk together the flour, cinnamon, nutmeg, cloves, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
If making streusel, combine streusel ingredients and sprinkle over the batter.
Pour the batter into a greased and floured loaf pan.
Cover the pan loosely with plastic wrap and let it ferment at room temperature for 4-8 hours, or until puffy and slightly risen. The exact time will depend on your starter’s activity and room temperature.
Preheat your oven to 350°F (175°C).
Bake for 50-60 minutes, or until a wooden skewer inserted into the center comes out clean. If the top browns too quickly, tent it with foil.
Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.
If making glaze, whisk together powdered sugar, milk, and vanilla until smooth. Drizzle over the cooled bread.
Notes
You can use sourdough discard instead of active starter, but the rise may be less pronounced.
For pumpkin sourdough muffins, reduce baking time to 20-25 minutes.
Adjust spices to your preference.
Ensure your sourdough starter is active and bubbly before using for best results.