01 - Preheat the oven to 350°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, baking powder, salt, cinnamon, ginger, nutmeg, and cloves. Set aside.
03 - In a large bowl, cream together butter and sugar until light and fluffy, about 2 minutes.
04 - Beat in the egg and vanilla extract until fully incorporated.
05 - Gradually add the dry ingredients to the wet mixture, mixing just until combined.
06 - Scoop tablespoon-sized balls of dough onto prepared baking sheets, spacing them 2 inches apart. Flatten each ball slightly with the bottom of a glass or your palm.
07 - Bake for 11-13 minutes, until edges are just golden. Cool on the tray for 5 minutes, then transfer to a wire rack to cool completely.
08 - Whisk together powdered sugar, milk, and vanilla until smooth and drizzle-able. Stir in the chopped hazelnuts.
09 - Drizzle over cooled cookies. Allow the drizzle to set before serving.