Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Cream together the softened butter, brown sugar, and granulated sugar using a mixer until light and fluffy.

Incorporate the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

Combine flour, baking powder, baking soda, and salt in a bowl. Gradually add to the wet mixture until just combined.

Mix together the brown sugar and cinnamon for the filling and set aside.

Divide dough into two portions and roll out one portion to ¼-inch thickness. Cut into 3x4-inch rectangles.

Place one tablespoon of filling on half of the rectangles, and cover with other dough pieces, crimping edges with a fork.

Transfer cookies to the baking sheet and bake for 12-15 minutes until edges are golden.

Cool cookies on the baking sheet for 5 minutes before transferring to a wire rack.

Whisk together powdered sugar and milk for the drizzle and pour over cooled cookies.