Place the butter in a light-colored saucepan over medium heat. Stir often as it melts, then foams, then starts to turn golden with brown specks forming at the bottom. Once it smells nutty and the color deepens, remove from heat immediately to prevent burning. Pour into a heat-safe bowl and let cool for 10–15 minutes before mixing with sugars. Use a silicone spatula to scrape up all the browned milk solids from the bottom of the pan — that’s where the flavor is.

Whisk the cooled brown butter with brown sugar, granulated sugar, pumpkin puree (blotted dry if too runny), egg yolk, and vanilla extract until smooth and glossy.

In another bowl, whisk together flour, cornstarch, cream of tarter, baking soda, baking powder, salt, cinnamon, ginger, nutmeg, and cloves. Slowly fold this into the wet mixture until just combined.

Cover the bowl that the dough is in with plastic wrap or a fitted cover and chill for at least 45–60 minutes. Chilling ensures the cookies don’t overspread and enhances the flavor.

Preheat oven to 350°F (175°C). Mix the cinnamon-sugar coating in a shallow bowl. Scoop ~2 tbsp of dough, roll into balls, and coat generously.

Bake 9–10 minutes until edges are set and tops are crackly. Cookies will look slightly underdone in the center. Let them cool on the sheet for 5 minutes before transferring to a wire rack and let them completely cool before serving.