Often a classic around the holidays, thumbprint cookies are widely popular because of the variety of fillings to choose from to fill that shallow hole. Whether filled with a favorite jam, peanut butter, or a Hershey's kiss, thumbprint cookies remain a class cookie to many.
Adapted with permission from the publisher, Wiley, from Cookies at home with The Culinary Institute of America. Copyright © 2011
Preheat the oven to 350 degrees. Line 2 baking sheets with parchment paper.
In the bowl of a stand mixer fitted with a paddle attachment, gently blend the butter, sugar, and salt on low speed until light and fluffy, about 4-5 minutes. In a medium bowl, whisk together the egg, egg yolk, and vanilla to combine. Gradually add the batter mixture, scraping down the bowl after each addition. Add the flour all at once and mix on low just to incorporate,
Scoop balls of about 1 tablespoon of dough onto the prepared baking sheets about 1 inch apart. Dip your finger in a small amount of water and press an indentation in the center of each cookie. Using a small spoon, fill the indentations with the jam. Bake until lightly browned around the edges, about 10-12 minutes. Rotate and switch the baking sheets as necessary for even baking.
Allow the cookies to cool for a minute on the baking sheet then transfer, using a spatula, to a cooling rack and allow to cool completely. Store the cookies in an airtight container.