8 tablespoons (112 g) unsalted butter, at room temperature
1/3 cup (38 g) confectioners’ sugar
1 egg yolk (25 g), at room temperature
1 teaspoon pure vanilla extract
1/8 teaspoon kosher salt
1 1/4 cups (175 grams) all purpose gluten free flour (I used Better Batter)
1/2 teaspoon xanthan gum (omit if your blend already contains it)
1/4 cup (50 g) granulated sugar
Seedless strawberry or apricot jam, for filling
Preheat your oven to 325°F. Line a large rimmed baking sheet with unbleached parchment paper and set it aside.
In a large bowl with a handheld mixer or the bowl of a stand mixer fitted with the paddle attachment, place the butter and beat until light and creamy. Add the egg yolk, confectioners’ sugar, vanilla and salt, mixing to combine well after each addition. Add the flour and xanthan gum, and mix until just fully combined. The cookie dough should be thick but not stiff.
Scoop the dough into portions about 2 teaspoonful each with a 1-inch cookie scoop or 2 spoons and place about 1 1/2-inches apart on the prepared baking sheet. Roll each mound of dough lightly into a ball, without packing the dough, then roll each ball in the granulated sugar to coat on all sides, and replace on the baking sheet. Using an index finger, dowel or the back end of a wooden spoon, poke a deep hole in the center of each ball about 1/2-inch wide and 3/4-inch deep. Fill each of the holes with the jam. Do not chill the dough.
Place the baking sheet in the center of the preheated oven and bake until the cookies are set and just beginning to brown around the edges (10 to 12 minutes). Remove from the oven and allow to cool on the baking sheet for at least 10 minutes or until firm.
P.S. Evernote users, don’t forget to click here for a free downloadable Evernote version of this gluten free jam Thumbprint cookies recipe.