By Siobhan Adcock, Epicurious, December 2011
Editor's note: This recipe appears as part of our editors' Christmas Cookie Swap, 10 beloved holiday recipes from the editors of Epicurious and Gourmet Live.
Make sure to make a deep impression in the dough with your thumb or a small pestle, and don't overfill the hole with jam, as these cookies will flatten and spread in the oven. Also, be sure to leave plenty of room in between the dough on the cookie sheet. Use a doily as a stencil to dust the confectioners' sugar in a festive pattern. [I just use a sieve and shake it on. -chaz]
Yield: Makes about 2 dozen cookies. [Using my purple scoop I get three dozen. Maybe 38. -chaz]
Position a rack in the upper third of the oven and a second rack in the lower third then preheat to 350°F. [Hah! Don't warm up the oven yet, you've got an hour or more until anything's going in. -chaz] Line 2 baking sheets with parchment paper.
In a large bowl, sift together the flour, baking soda, and salt.
In the bowl of a stand mixer fitted with the paddle attachment, combine the butter and sugar and beat on medium speed, scraping the bowl occasionally, until light and fluffy, about 2 minutes. Add the egg and vanilla and beat until fully incorporated, about 1 minute. With the mixer on low, add the flour mixture, and stir until just combined. Shape the dough into a disc, wrap it in plastic, and chill at least 1 hour and up to 24 hours.
Roll the dough into 1-inch balls and arrange on baking sheets, leaving about 3 inches between cookies. Using your thumb or the round end of a small pestle, make a well in the center of each cookie. Using a teaspoon, fill each well with jam, being careful not to overfill the wells. Bake, switching the cookies between the upper and lower racks about halfway through baking, until golden, about 15 minutes. Cool the cookies on baking sheets for 10 minutes before transferring to a wire rack to cool completely. Dust with confectioners' sugar. Continue baking cookies on cooled baking sheets.
DO AHEAD: The cookies can be baked ahead and stored, in an airtight container at room temperature, up to 3 days.
[Taken from https://www.epicurious.com/recipes/food/views/siobhans-thumbprint-cookies-368715]
[Aug. 2018. These have joined my short list of "Standard Cookies." They only make about three dozen cookies. I usually try to make two or more batches in different flavors.]