2 1/2 cups all-purpose flour
1/4 teaspoon baking soda
1/4 teaspoon kosher salt
1 cup unsalted butter (2 sticks), at room temperature
3/4 cup sugar
1 large egg
1 teaspoon pure vanilla extract
apricot jam or raspberry jam
In a large bowl, whisk together the flour, baking soda, and salt. Set aside.
In another bowl, beat the butter and sugar until smooth using an electric mixer. Add the egg and beat until fluffy, about 2 minutes. Beat in the vanilla.
With the mixer on low, gradually add the flour mixture, mixing until just incorporated (the dough will be stiff). Shape dough into a disk, wrap in plastic wrap and refrigerate for at least 1 hour or until needed (can be stored this way for up to 3 days).
Roll the basic sugar cookie dough into tablespoon-size balls and place on baking sheets lined with [archment paper. Make a well in each ball by pressing your thumb in the center. Fill the wells with apricot jam, raspberry jam or any other fruit jam of your choice.
Bake in a 350° F pre-heated oven until just beginning to brown, around 15 to 18 minutes.
Cool slightly on baking sheets, then transfer to wire racks to cool completely.