• Preheat oven to 350°F (177°C). Line two baking sheets with parchment paper and set aside.
• Place the pure pumpkin into a fine mesh strainer set over a bowl. Allow it to drain for at least 10–15 minutes to remove excess liquid.*
• In a large bowl, whisk together the flour, baking powder, baking soda, salt, pumpkin pie spice, cinnamon, and ginger. Set aside.
• In a separate large bowl, use a hand mixer on medium speed to cream the softened butter, brown sugar, and granulated sugar until smooth, about 2 minutes.
• Add the egg and beat on high speed until combined, about 1 minute, scraping down the sides of the bowl as needed.
• Add the milk and strained pumpkin, then mix on high speed until combined. The mixture may look slightly lumpy—this is normal.
• Add the dry ingredients to the wet ingredients, mixing on low speed until just combined. The dough will be thick and sticky. Using a 2-tablespoon scoop, drop the dough onto the lined baking sheets, about 2 inches apart.
• Bake for 14–15 minutes, or until the edges appear set but the center is still soft.
• Remove from the oven and let cookies cool completely.

Brown Butter Buttercream

• In a medium saucepan, melt the butter over medium heat. Continue cooking, stirring frequently, until the butter foams and brown bits form at the bottom. This takes about 5-7 minutes. Watch closely to avoid burning. When the butter reaches a warm amber color and has a nutty aroma, remove it from heat.
• Pour the browned butter into a heat-safe bowl and chill it in the refrigerator for 20-30 minutes.
• Once the browned butter is cooled, place it in a stand mixer fitted with the whisk attachment. Whip the butter on medium-high speed for about 1 minute.
• Gradually add the confectioners' sugar. Then, add the vanilla.
• Reduce the mixer speed to low. Add buttermilk, one tablespoon at a time, until the frosting reaches a smooth and spreadable consistency. Whip the frosting on high speed for 1–3 minutes, until light and fluffy.

Assembly

• Once the cookies are completely cooled, spread or pipe a generous amount of brown butter buttercream on the bottom of one cookie. Top with a second cookie to form a sandwich. Repeat with remaining cookies and buttercream.