Brown the butter. Place in a small pan, melt and heat to a boil. Simmer until butter is brown and fragrant, about 10 minutes. Immediately pour into a heat proof mixing bowl. Note that the butter will go from unchanged to browned very quickly so keep an eye on it or it can burn.

Add brown sugar to the brown butter and whisk to blend. Add pumpkin puree and whisk to incorporate. Make sure the mixture is just warm (not hot enough to cook an egg), then add egg.

Combine dry ingredients and stir into the butter mixture.

Cover and chill until firm, about an hour.

Preheat the oven to 350 F and line a baking sheet with parchment.

In a small bowl, mix the cinnamon and sugar to form the topping.

Form dough into generous 1-inch balls. Roll the cookie balls in the sugar mixture until covered all around. Set onto the parchment, 9-12 per cookie sheet.