Make the dough: Beat butter and sugar until light and fluffy. Add the egg and mix until smooth.

In another bowl, whisk flour, baking powder, and salt. Gradually add to the butter mixture. Stir in the milk until the dough comes together soft but not sticky.

Roll it out: On a lightly floured surface, roll dough into a rectangle about ¼-inch thick.

Add filling: Brush melted butter over the dough, then sprinkle evenly with brown sugar and cinnamon.

Roll: Starting from the long side, roll the dough tightly into a log. Wrap in plastic wrap and refrigerate 30–45 minutes.

Slice & bake: Preheat oven to 350°F (175°C). Slice dough into ½-inch rounds and place on parchment-lined baking sheets. Bake 10–12 minutes, until edges are just set.

Glaze: Whisk powdered sugar with milk until smooth. Drizzle over warm cookies and let set before serving.