Thick, chewy pumpkin snickerdoodles made with nutty brown butter and a generous cinnamon sugar coating. The pumpkin is cooked down in the pan with the butter rather than blotted, which drives off the excess moisture and concentrates the flavor at the same time.
Use plain canned pumpkin puree rather than pumpkin pie filling, which is already sweetened and spiced.
The reduction time varies a great deal with pan width, so rely on the spoon trail rather than the clock. Once the water has cooked off the pan heats quickly, and the browned milk solids underneath will scorch, so pull it off the heat as soon as the trail holds.
Only the yolks are used because whole eggs bring extra water into a dough that already carries moisture from the pumpkin.
Cream of tartar provides the tang and soft crumb of a true snickerdoodle. If you have none, replace it and the baking soda with 2 1/4 tsp baking powder, though the flavor will be milder.
If the cookies bake up puffy and cakey, the pumpkin needed longer in the pan. If they spread thin, the dough was too warm and needs a longer chill.
Store cooled cookies in an airtight container at room temperature for up to 3 days, with parchment between layers to protect the coating. A slice of sandwich bread in the container keeps them soft.
Baked cookies freeze for up to 2 months. Portioned dough balls also freeze well before coating. Thaw in the refrigerator overnight, let them sit at room temperature for 15 minutes, then roll in the spiced sugar and bake as directed.