Pour 2 cups of apple cider into a medium saucepan. Simmer over medium heat until reduced to ½ cup for about 10-15 minutes.

Cream together ½ cup softened butter and 1 cup brown sugar until light and fluffy. Add 1 egg and vanilla extract, mixing well.

Whisk together 2 cups flour, 1 tsp baking soda, 1 tsp baking powder, and ½ tsp salt in a separate bowl.

Gradually mix dry ingredients into the wet mixture, alternating with ½ cup whole milk until just combined.

Preheat oven to 350°F (175°C). Drop rounded balls of batter onto parchment-lined sheets. Bake for 10-12 minutes.

Beat ½ cup softened butter until creamy, then add 2 cups powdered sugar and ¼ cup apple cider reduction, mixing until smooth.

Pair cooled cookies, pipe buttercream on one side, drizzle with caramel, and top with another cookie.