1-Whisk the flour, baking powder, and salt in a medium bowl; set aside.

2-Beat the butter and sugar in a large bowl until creamy, about 2 minutes; add the egg and vanilla, and beat until combined, about 1 minute.

3-Gradually add the dry ingredients to the wet mixture, mixing on low until combined; if the dough feels too soft, add 1 extra tablespoon of flour.

4-Divide the dough into two equal parts and roll each into a 9×7 inch rectangle, about 1/4 inch thick, on a floured surface.

5-Spread 1 tablespoon of melted butter over each rectangle, then mix the sugar and cinnamon and sprinkle it evenly over the top.

6-Roll each rectangle tightly into a 9-inch log, smoothing any cracks as you go; chill the logs for at least 2 hours or freeze up to 3 months.

7-Preheat your oven to 350°F (177°C) and line baking sheets with parchment or silicone mats.

8-Slice the logs into 1/2 inch thick pieces and place them 2 inches apart on the baking sheets.

9-Bake for 10 11 minutes until the edges are lightly browned; cool on the baking sheet for 5 minutes, then transfer to a wire rack.

10-Whisk the icing ingredients and drizzle over the cooled cookies.

11-Store the iced cookies at room temperature for up to 5 days.