Preheat oven to 300 F.
In a medium-sized mixing bowl, mix butter, brown sugar, and white sugar until fully combined.
Mix in the egg yolks.
Mix in pureed pumpkin, flour, cardamom, allspice, cinnamon, clove, ginger, black pepper, and salt until it a thick dough forms.
Scoop out balls of dough about two teaspoons in size and place them on a parchment- or Silpat-lined cookie sheet about one inch apart from each other.
Use your thumb or pointer finger to make a divot in the center of each ball of dough.
Bake for 25 minutes or until the cookies darken slightly in color.
Remove cookies from the oven and, while they are still hot, deepen any of the divots with your finger as needed.
Place on a cooling rack.