Morello Cherry Jam Tart Squares

3 cups flour 3/4 cup granulated sugar 1/2 teaspoon baking powder Pinch of salt 3/4 cup unsalted butter, cut into cubes 3 large egg yolks 1 jar of Les Confitures à l'Ancienne Morello Cherry Conserve Powdered sugar for dusting (optional)
Preheat oven to 375°. In a food processor, whirl together flour, granulated sugar, baking powder, salt, and butter until dough is very crumbly, about 2 minutes. Add yolks and pulse until dough just comes together. Or, you can combine ingredients (dry first, then the yolks) in a large bowl using a pastry blender.
Grease a 10-in.baker's sheet pan with butter or cooking spray. Press about three-quarters of dough into bottom of pan and half way up the sides. Spread jam over dough, leaving a 1/2-in. border around edge. Crumble remaining dough over jam to form topping. Bake until lightly browned and jam is bubbling, about 40 minutes. Let cool 15 minutes before removing from pan.