In the bowl of your stand mixer, cream together the softened butter, and sugars with the paddle attachment on medium speed until smooth.
Lower the mixer speed to low speed and add the sourdough discard, pumpkin puree, and vanilla extract. Mix until thoroughly combined, about 30 seconds.
Add the bread flour, kosher salt, cinnamon, nutmeg, ginger, baking soda and cloves. Mix on low speed until just combined.
Wrap the dough in wax paper and refrigerate for 2-3 hours.
Preheat the oven to 350°F (180°C).In a small bowl stir together the ingredients for the cinnamon-sugar coating. Remove the dough from the refrigerator and roll it into balls, about 2 tablespoons of dough each.Roll the cookie dough balls in the cinnamon-sugar mixture coating thoroughly and place them on the baking sheet about two inches apart.
Bake for 12 to 14 minutes or until the edges are lightly browned but the center is still soft.Allow the cookies to cool for at least 5 minutes before transferring them to a wire rack to cool completely.
Notes
Storage: Baked Sourdough Pumpkin Cookies can be stored in an airtight container at room temperature for two to three weeks.Tips
Use a kitchen scale to weigh your ingredients rather than the cup measurements. In baking accuracy matters. If you don't have one this is my favorite kitchen scale, because the display pulls out making it easy to see even if you are using a large bowl.
Make sure all of the ingredients are at room temperature. This ensures the ingredients mix evenly and will give you the best final texture.
Don't over-mix the dough once the sourdough discard and flour has been added. Over-mixing will create too much gluten and cause the cookies to be tough.
You must chill the dough for at least 2-3 hours before baking. Because we browned the butter the fats need to re-solidify. Chilling also allows the flour to absorb more liquid further solidifying the dough. If the dough is baked without chilling it first, the cookies will spread while baking and become thin, hard, and crispy.
To quickly portion out the dough use a knife to cut the chilled dough into smaller pieces.
For a crispier cookie, bake them for slightly longer (about 2-3 minutes more).
Baking times for all recipes are only suggestions. The actual baking time will vary depending on your oven. It is helpful to know your oven and worth purchasing an inexpensive oven thermometer. Oven temperatures can vary as much as 50 degrees plus or minus.
Allow the cookies to cool for 5 minutes before transferring them to a wire rack. These pumpkin cookies are soft and fluffy when they first come out of the oven. They may fall apart if you try to move them too soon.