tbsp. unsalted butter, cut into ½″ cubes and chilled
tsp. baking powder
tsp. kosher salt
eggs, lightly beaten
12-oz. jar plum preserves
Process flour, ¼ cup sugar, butter, baking powder, and salt in a food processor until pea-size crumbles form. Add 2 eggs and ¼ cup ice-cold water; pulse until dough forms. Form into a disk; wrap; chill for 1 hour. Finely chop remaining sugar and walnuts in a food processor; Set aside. Puree preserves in processor. 2. Heat oven to 375°. Cut dough into thirds; roll each into an 11″ × 7″ rectangle; line an 11″ × 7″ baking dish with a rectangle. Spread over half the preserves; sprinkle with one-third walnuts. Top with second rectangle; spread over remaining preserves and half remaining walnuts. Top with last rectangle, and prick with tines of a fork. Brush with remaining egg; sprinkle with remaining walnuts. Bake until golden, 25–30 minutes.