- 2 1/2 cups all-purpose flour
- 1 teaspoon salt
- 2 sticks (1/2 pound) unsalted butter, softened
- 1 cup sugar
- 1 large egg
- 1 teaspoon pure vanilla extract
- About 2 tablespoons seedless raspberry jam
- About 2 tablespoons apricot preserves
- About 2 tablespoons strawberry preserves
- Equipment: a 1/2-inch-thick wooden spoon handle or dowel
Whisk together flour and the salt. Beat butter and sugar with an electric mixer until very pale and fluffy, about 4 minutes, then beat in egg and vanilla. At low speed, mix in flour mixture in 3 batches just until a dough forms. Divide dough in half and form each piece into a 6-inch disk, then chill, wrapped in plastic wrap, until firm, about 1 hour.
Preheat oven to 350°F with rack in middle. Line 2 large baking sheets with parchment paper.
Roll 3 separate level teaspoons of dough each into a ball, then flatten each ball slightly (to 1 inch wide and less than 1/2 inch thick). Arrange them in a triangle on baking sheet with edges touching in center, then make a deep indentation in center of each round with wooden spoon handle. Make more cookies, arranging them 1 inch apart on baking sheets.
Fill indentations in each cookie with about 1/8 teaspoon jam (each cookie should have 3 different fillings), avoiding any large pieces of fruit.
Bake until cookies are baked through and golden-brown on edges, 15 to 20 minutes. Cool on baking sheets 5 minutes, then transfer to racks to cool completely.
Bake more batches on cooled baking sheets lined with fresh parchment.
Dough can be chilled up to two days. Cookies keep, layered between sheets of parchment, in an airtight container at room temperature 1 week.