Step 1: Blot the pumpkin puree by spreading it on paper towels to remove excess moisture until you have 1/3 cup of concentrated puree left.
Step 2: Brown the butter in a saucepan until nutty and golden, then let it cool to room temperature.
Step 3: Cream the cooled browned butter with brown sugar and granulated sugar in a large bowl until smooth.
Step 4: Mix in the blotted pumpkin, egg yolk, and vanilla extract until fully incorporated.
Step 5: Whisk the dry ingredients (flour, baking soda, salt, and spices) in a separate bowl.
Step 6: Gradually fold the dry ingredients into the wet mixture until no flour streaks remain, being careful not to overmix.
Step 7: Chill the dough in the refrigerator for at least 30 minutes to improve texture and prevent spreading.
Step 8: Preheat oven to 350°F (175°C) and line baking sheets with parchment paper.
Step 9: Scoop 2-tablespoon sized balls of dough onto the sheets and bake for 10-12 minutes until edges are set.
Step 10: Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.