Mocha Moon Cookies

1.  For the cookies, whisk together the dry ingredients in a medium bowl. In a large bowl, cream the butter with the sugars until smooth but not fluffy. Stir in the egg and vanilla. Add the dry ingredients and mix until just incorporated.2.  For the dough into two long rolls, about 1 inch in diameter. Wrap well in plastic and freeze until firm, at least 1 hour and up to 1 month.3.  Preheat the oven to 350˚. Line baking sheets with parchment paper or nonstick liners (you’ll have four baking sheets worth of cookies). Use a sharp knife to thinly slice the dough into ¼ inch thick coins. Place them on the baking sheets, 1 inch apart.4.  Bake, rotating the pans from top to bottom and front to back halfway through, until the cookies have puffed and settled down again, about 10 minutes.5.  Let cool briefly then transfer to a wire rack to cool completely.6.  For the glaze, in a small bowl, dissolve the coffee granules in the hot water. Mix in the confectioners’ until smooth, then thin with a few drops of milk.7.  Brush the cookies with the coffee glaze, then sprinkle each cookie with a small pinch of fleur de sel if desired. Let rest until the glaze hardens, about 30 minutes. Store the cookies in an airtight container for up to 1 week. Find out more about this recipe on Mom Appetit's blog.