In a large bowl, whisk together the sourdough discard, pumpkin purée, granulated sugar, brown sugar, olive oil (or butter), egg yolks, and vanilla extract until smooth.
In a separate bowl, sift together the all-purpose flour, soft wheat flour, cream of tartar, baking soda, salt, cinnamon, and nutmeg.
Gradually mix the dry ingredients into the wet mixture until a soft dough forms.
Cover the bowl and let the dough rest at room temperature for 2-3 hours, allowing sourdough fermentation to develop. This step is optional.