Reduce Apple Cider: Pour 2 cups of apple cider into a saucepan and simmer over medium heat until it thickens and measures about ¼ cup, about 15-20 minutes. Let cool.

Brown Butter: Melt 20 tablespoons of unsalted butter over low heat until golden brown and nutty, about 8-10 minutes. Allow to cool for at least 30 minutes.

Mix Dry Ingredients: Whisk together 2 ½ cups of all-purpose flour, 1 teaspoon of baking powder, 1 teaspoon of baking soda, 1 tablespoon of cornstarch, 1 teaspoon of pumpkin spice, and ½ teaspoon of salt.

Combine Wet Ingredients: Whisk the cooled brown butter with ½ cup of granulated sugar and ½ cup of light brown sugar until creamy. Add in 1 large egg, 1 egg yolk, the cooled reduced apple cider, and 1 teaspoon of vanilla extract.

Combine Mixtures: Gradually add dry ingredients to the wet mixture until just combined. Let dough rest for at least 30 minutes.

Preheat Oven: Preheat the oven to 375°F (190°C) while the dough rests. Prepare a baking sheet with parchment paper.

Shape Cookies: Use a cookie scoop to portion out dough onto the baking sheet, leaving 3 inches of space. Aim for 12-16 mounds.

Bake: Bake cookies for 9-11 minutes, until edges are set and centers are puffy. Monitor closely.

Cool: Let the cookies cool on the baking sheet for 5 minutes before transferring to a wire rack.

Assembly: Brush cookies with melted apple cider butter, roll in cinnamon sugar, and drizzle with glaze.