Make the Pumpkin Cookies
Preheat oven to 375°F (190°C). Line baking sheets with parchment.
Whisk together flour, baking powder, baking soda, and spices.
Cream butter, granulated sugar, and brown sugar until fluffy.
Beat in egg, vanilla, and pumpkin puree.
Mix in dry ingredients just until combined.
Drop 1.5 tbsp scoops of dough on sheets, 2 inches apart.
Bake 10–12 minutes, until edges are set. Cool completely on a wire rack.
Make the Coffee Syrup
Stir brewed coffee, sugar, and Kahlua until sugar dissolves.
Prepare the Mascarpone Cream Frosting
Beat mascarpone, heavy cream, powdered sugar, and vanilla until fluffy and soft peaks form. Do not overbeat.
Assemble
Brush flat side of cooled cookies with coffee syrup.
Pipe or spoon mascarpone cream onto half of the cookies.
Top with remaining cookies to form sandwiches.
Dust tops with cocoa powder.