Directions

1.    Combine the flour, sugar, cardamom and salt in a processor. Pulse to combine. Add butter and pulse to pea size. Sprinkle 3 tablespoons water over flour; process 3 to 4 seconds until starting to come together (if dough looks very sandy, add water and pulse a few more times until clumping but slightly loose). Turn out onto a large sheet of plastic wrap. Bring wrap up and cover top of dough; press to form 7-inch disk. Chill until cold.
2.    Divide dough into 6 equal pieces. Roll out on lightly floured board to form 1/8-inch thick circles approximately 5-inches in diameter. Line a baking sheet with parchment paper; transfer circles to sheet. Spoon cookie crumbs into center of circles.
3.    In a large bowl, gently toss blueberries, nectarines, sugar and cornstarch. Mound fruit evenly in center of each circle, leaving a 1-inch border around edge. Bring pastry up and over filling just to form a 1-inch border. Brush pastry lightly with egg mixture and sprinkle with sugar. Chill until cold.
4.    Position oven rack in lower third of oven; heat to 425 F. Bake crostata 35 minutes until center lightly bubbles and crust is deep golden. Cool 15 minutes. Serve warm with gelato or lightly sweetened whipped cream.