In a medium mixing bowl, whisk together the all-purpose flour, pumpkin pie seasoning, baking soda, and salt until everything is well combined. Set this bowl aside to use after the wet ingredients have been prepared.

Melt 1/2 cup (1 stick) of unsalted butter in a medium-sized saucepan over medium heat, stirring constantly until it turns a medium brown color and gives off a sweet, nutty aroma (2-4 minutes). Remove from the heat and immediately add the remaining 1/4 cup of softened butter, stirring until it is fully melted. Add the granulated sugar and brown sugar to the mixture, stirring until well combined, though the sugars may not fully dissolve. Let the pan cool for about 5 minutes. If you used a heavy or cast iron pan, let it cool completely, or transfer the mixture to a large mixing bowl to speed up the cooling.

Once the butter and sugar mixture has cooled, add in the vanilla extract, pumpkin puree, and unfed sourdough starter. Whisk all together until the mixture is completely smooth. I find whisking here helps ensure there are no streaks of pumpkin or sourdough left in the dough.

Slowly add the dry ingredients from Step 1 into the bowl with the wet mixture from Step 3. Use a rubber spatula and stir until just combined—avoid overmixing. Next, fold in the semi-sweet chocolate chips until they are evenly distributed throughout the dough. These will melt into gooey pockets as the cookies bake. I like to reserve a few chocolate chips to press on top of the dough balls for a more attractive look.

Cover the finished cookie dough with plastic wrap and refrigerate for at least 1 hour, or up to 24 hours. This step helps the flavors meld and makes it easier to form the dough into balls. If you have the time, I recommend chilling overnight for even better texture—patience really pays off here!

Preheat your oven to 375°F (190°C). Line two large cookie sheets with parchment paper. Roll the chilled dough into 1¼-inch balls and arrange them in a 3x4 formation on the prepared sheets, ensuring enough space for the cookies to spread. Bake for 12-14 minutes until the cookies are puffed and lightly golden. They'll look puffy in the oven but will settle as they cool.

Allow the baked cookies to cool on the baking sheet for 5 minutes. Then, transfer them to a wire rack to cool completely before serving. I sometimes sneak a warm cookie straight from the sheet—they’re irresistible when the chocolate is still melty!