Brown the butter: Melt butter in a saucepan until golden brown specks form and a dense foam appears. Cool for 20-30 minutes until just warmer than room temperature.

Mix wet ingredients: In a large bowl with cooled brown butter, whisk together brown sugar, granulated sugar, pumpkin puree, egg yolk, and vanilla extract until smooth.

Combine dry ingredients & mix: In a separate bowl, whisk together flour, pumpkin pie spice, espresso powder, and salt. Add this to the wet ingredients, along with the quick oats. Fold until just combined. Refrigerate dough for 30 minutes.

Preheat oven & prep sheets: Preheat your oven to 350°F (175°C). Line two large cookie sheets with parchment paper.

Bake cookies: Use a 1-oz cookie scoop to portion dough, placing scoops 3 inches apart on prepared sheets. Bake for 9-11 minutes until edges are brown and centers are puffed and golden. Let cool on the sheet for 2 minutes before transferring to a wire rack.

Make icing: Sift powdered sugar into a bowl. Add cream, salt, vanilla, and espresso powder. Whisk until thick and drizzly. Add more cream if needed.

Ice cookies: Dip the top of each cooled cookie into the icing, letting it coat only the bumps and cracks. Place on a rack to let the icing set.