My son loves shortbread. He had his first taste of it when he was in Scotland on a missions trip when he was 16. He brought me a shortbread mold as a thank you for getting him all together for his trip and identically shaving all his hair off before he went. (I had never used the hair clippers before and he wanted me to cut his hair short, I did, right to the scalp with the first pass and then there was not turning back, had to match up the rest of it.)
1Dissolve the espresso in the boiling water, and set aside to cool to tepid.
Working with a stand mixer, preferably fitted with a paddle attachment, or with a hand mixer in a large bowl, beat the butter and confectioners’ sugar together on medium speed for about 3 minutes, until the mixture is very smooth.
2Beat in the vanilla and espresso, then reduce the mixer speed to low and add the flour, mixing only until it disappears into the dough.
Don’t work the dough much once the flour is incorporated. Fold in the chocolate chips with a sturdy rubber spatula.
3Using the spatula, transfer the soft, sticky dough to a gallon-size zipper-lock plastic bag. Put the bag on a flat surface, leaving the top open, and roll the dough into a 9 x 10 1/2 inch rectangle that’s 1/4 inch thick.
As you roll, turn the bag occasionally and lift the plastic from the dough so it doesn’t cause creases. When you get the right size and thickness, seal the bag, pressing out as much air as possible, and refrigerate the dough for at least 2 hours, or for up to 2 days.
4Position the racks to divide the oven into thirds and preheat the oven to 325 degrees F. Line two baking sheets with parchment or silicone mats.
Put the plastic bag on a cutting board and slit it open. Turn the firm dough out onto the board (discard the bag) and, using a ruler as a guide and a sharp knife, cut the dough into 1 1/2-inch squares. Transfer the squares to the baking sheets and carefully prick each one twice with a fork, gently pushing the tines through the cookies until they hit the sheet.
5Bake for 18 to 20 minutes, rotating the sheets from top to bottom and front to back at the midway point. The shortbreads will be very pale–they shouldn’t take on much color. Transfer the cookies to a rack.
If you’d like, dust the cookies with confectioners’ sugar while they are still hot. Cool the cookies to room temperature before serving.