In a large bowl, cream ½ cup butter and ½ cup brown sugar till light and fluffy.
Beat in the egg and vanilla extract until fully blended.
Whisk together flour, baking powder, salt, and cinnamon in a separate bowl.
Slowly add dry ingredients to wet mixture until a soft, slightly sticky dough forms.
Wrap dough in plastic wrap and refrigerate for 30 minutes.
Roll out dough into a ¼-inch thick rectangle on a floured surface.
Brush with melted butter and sprinkle cinnamon-sugar mixture evenly on top.
Roll into a log, slice into ½-inch cookies and place on parchment-lined tray.
Bake at 350°F for 10-12 minutes until edges are light golden.
Cool briefly on tray before transferring to wire racks.
Mix glaze ingredients and drizzle over cooled cookies before serving.
Notes
Store leftover cookies in an airtight container. Add a slice of bread to retain freshness. Freeze for longer keeping and thaw at room temp for soft texture.