In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy (about 2-3 minutes).

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

In a separate bowl, combine the flour, baking powder, baking soda, and salt. Gradually blend this dry mixture into the wet ingredients just until everything is combined.

In a small bowl, mix together the brown sugar and cinnamon. Set aside for later.

Divide the dough into two equal parts. Roll out one portion on a floured surface to about 1/4 inch thick. Cut the dough into 3×4 inch rectangles. Repeat with the second portion.

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

Place a tablespoon of the brown sugar filling in the center of a rectangle, cover it with another rectangle, and seal the edges.

Bake for 12-15 minutes, or until lightly golden. Cool for about 5 minutes on the baking sheet before transferring to a wire rack.

To make the icing, mix together the powdered sugar and 1-2 tablespoons of milk until smooth. Drizzle over the cooled cookies and add sprinkles if you’re feeling festive!