10 tablespoons unsalted butter, at room temperature
6 tablespoons preserves (any flavor)
Preheat the oven to 375 degrees F. Line an 8-inch-square baking dish with aluminum foil, leaving an overhang. Whisk the flour, sugar and salt in a bowl. Work in the butter with your fingers to make a crumbly dough.
Refrigerate 2 tablespoons of the dough for topping. Press the remaining dough into the baking dish; freeze until firm, about 10 minutes.
Bake the crust, 15 minutes. Spread the preserves on top, leaving a 1/2-inch border; crumble the reserved dough on top. Return to the oven and bake until the edges are golden brown, 25 more minutes. Let cool 20 minutes, then lift out of the pan and cut into squares.