Making the Cookies

• Whisk the flour, baking powder, and salt together in a medium bowl. Set aside.
• In a large bowl using a handheld or a stand mixer fitted with a paddle attachment, beat the butter and sugar together on high speed until completely smooth and creamy, about 2 minutes. Add the egg and vanilla and beat on high speed until combined, about 1 minute. Scrape down the sides and up the bottom of the bowl and beat again as needed to combine.
• Add the dry ingredients to the wet ingredients and mix on low until combined. Dough will be a bit soft. If the dough seems too soft and sticky for rolling, add 1 more Tablespoon of flour.
• Divide the dough into 2 equal parts. Roll each portion out in a rectangle (about 9×7 inches) onto a floured silicone baking mat (or floured parchment paper) to about ¼" thickness. Spread 1 Tablespoon of melted butter onto each rectangle. Mix the granulated sugar and cinnamon together then sprinkle evenly over each.
• Working slowly, tightly roll up each rectangle into a 9-inch log. If the dough is cracking at all, use your fingers to smooth it out. Some cracks are OK. Chill the logs of dough for at least 2 hours (or freeze up to 3 months).
• Preheat oven to 350°F (177°C). Line a large baking sheet with parchment paper or a silicone baking mat.
• Remove dough logs from the refrigerator. Cut into ½ inch slices. Place slices onto baking sheets about 2 inches apart.
• Bake for 10-11 minutes, until lightly browned on the sides. Remove from the oven, allow to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely before icing.
• Whisk all of the icing ingredients together. Drizzle over cookies.
• Cover and store cookies at room temperature for up to 5 days.