By gilice, member
Posted: November 23rd, 2012
Whisk the flour, baking powder, and salt in a medium bowl until combined.
In a stand mixer fitted with the paddle attachment (or in a large mixing bowl with a hand-held electric mixer), beat the butter and sugar on medium speed until light and fluffy, 3 to 4 minutes. Scrape down the bowl and beater with a rubber spatula as needed. Combine the instant espresso and vanilla extract in a small bowl; stir to dissolve. Add the egg and espresso mixture to the mixer, and continue to mix until well blended, about 1 minute. Add the flour mixture and mix on low speed until well blended, about 1 minute more.
Turn the dough out onto a lightly floured work surface and gently knead until it's smooth with no air pockets. Using a large piece of plastic wrap as an aid, shape the dough into a 12-inch-long, 2-inch-wide log. Twist the ends of the plastic to compact and secure the log. To help the dough keep its shape, set it in an empty cardboard paper towel tube that's been slit lengthwise and freeze until very firm, at least 2 hours. Alternatively, give the log a quarter turn every 15 minutes during the first hour of freezing to keep it from flattening on one side. (At this point, the dough can be frozen for up to 1 month. Thaw in the refrigerator for 1 hour before slicing and baking.)
Position racks in the upper and lower thirds of the oven and heat the oven to 350 degrees F. Line 2 or more cookie sheets (preferably flat sheets with one raised edge) with parchment or nonstick baking liners.
Roll the log of dough in sanding sugar until evenly coated. Using a sharp, thin knife, slice the dough a scant 1/4 inch thick and set the cookies about 1 inch apart on the prepared sheets. If the dough becomes too soft to hold its shape when slicing, refreeze until firm; if it's too hard to slice, let it sit at room temperature until sliceable.
Bake two sheets at a time, rotating and switching their positions halfway through, until the edges and bottoms of the cookies are golden, 6 to 8 minutes. Let the cookies cool on their sheets on wire racks for about 5 minutes and then transfer them to the racks to cool completely.
In a small bowl, mix the confectioners' sugar, cream, and salt with a spoon or rubber spatula until well blended and smooth. Add vanilla extract or paste and food coloring, if using, and stir until well blended. If necessary, add more cream a drop at a time for a thin, spreadable consistency. (The glaze can be covered and refrigerated for up to 3 days. Bring to room temperature before using.)
Arrange the cooled cookies on a rack set over a large rimmed baking sheet. Dip the sides of each cookie to cover half or more of the cookie. Let excess glaze drip off and then transfer to the rack.
Alternatively, use a fork to drizzle the glaze over the cookies on the rack. Or partially fill one corner of a small, heavy-duty zip-top baggie with glaze, squeeze out the air, and seal the baggie. Cut off the corner and gently squeeze the bag to drizzle the glaze evenly over the cookies.
Let the cookies remain on the rack until the glaze sets up, about 3 hours.
Once they're set, serve the cookies or store in an airtight container for up to 3 days.