Step 1
Arrange racks in upper and lower thirds of oven; preheat oven to 350°. Line 2 large, rimmed baking sheets with parchment paper.
Step 2
Sift 2½ cups (313 g) all-purpose flour, ¼ tsp. baking soda, and ¼ tsp. kosher salt into a large bowl. Set aside.
Step 3
Beat 1 cup (2 sticks) unsalted butter, room temperature, and ¾ cup (150 g) granulated sugar in the bowl of a stand mixer fitted with the paddle attachment (or in a large mixing bowl with a hand mixer) on medium speed, scraping bowl occasionally, until light and fluffy, about 2 minutes (4 minutes if using a hand mixer). Add 1 large egg and 1 tsp. vanilla extract; beat until fully incorporated, about 1 minute. With mixer on low, add dry ingredients in stages, beating until just combined. Shape dough into a disk, wrap in plastic, and chill at least 1 hour and up to 24.
Step 4
Roll the dough into 1″ balls and arrange on prepared baking sheets, leaving about 3″ between cookies. Using your thumb, the round end of a small pestle, or the bottom of a measuring spoon, make a well in the center of each dough ball. Fill each indentation with ½ tsp. jam from ½ cup jam, such as raspberry, strawberry, or apricot, being careful not to overfill. Bake, switching cookie sheets between upper and lower racks about halfway through baking, until thumbprints are golden, about 15 minutes.
Step 5
Cool thumbprints on baking sheets for 10 minutes before transferring to a wire rack to cool completely. Dust with powdered sugar. Bake remaining cookie dough on cool baking sheets.
Do ahead: Thumbprint cookies can be baked 3 days ahead. Cool completely, then store in an airtight container at room temperature.
Photograph by Elliott Jerome Brown Jr., Prop Styling by Emma Ringness, Food Styling by Mieko Takahashi
Editor’s note: This recipe was originally printed in November 2011 as Siobhan’s Thumbprint Cookies. Head this way for more of our all-time-best Christmas cookie recipes →