1. Reduce apple cider: In a small saucepan, heat about 1/2 cup apple cider over medium heat until reduced by half (1/4 cup). Allow to cool.
2. Prepare the dough: Preheat the oven to 350°F (175°C). In a large bowl, cream together the room temperature butter, brown sugar, and granulated sugar until the mixture is smooth and creamy.
3. Add the egg and the reduced apple cider. Beat until well combined.
4. In the same bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
5. Gradually add the dry ingredients to the wet ingredients, mixing until a smooth dough forms.
6. Shape the cookies: Use a #20 cookie scoop or a regular spoon to form balls of dough. Place them on a parchment-lined baking sheet, spacing them apart.
7. Bake at 350°F (175°C) for 10 to 12 minutes, or until the edges are golden and the centers look set.
8. Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
9. Prepare the glaze: In a small bowl, mix the apple cider with the powdered sugar until you have a smooth glaze.
10.Drizzle or spread the glaze over the cooled cookies.