PEACH BLUEBERRY CAKE

Steps:

• Make pastry:
• Pulse together flour, sugar, baking powder, and salt in a food processor until combined. Add butter and pulse just until mixture resembles coarse meal with some small (roughly pea-size) butter lumps. Add egg and vanilla and pulse just until dough clumps and begins to form a ball, about 15 pulses.
• Press dough onto bottom and evenly (about 1/4 inch thick) all the way up side of springform pan with floured fingertips. Chill pastry in pan until firm, about 10 minutes.
• Make filling while pastry chills:
• Put oven rack in middle position and preheat oven to 375°F.
• Grind 2 tablespoons sugar with flour and tapioca in grinder until tapioca is powdery, then transfer to a large bowl and stir in remaining 6 tablespoons sugar. Add peaches, blueberries, and lemon juice and gently toss to coat. Spoon filling into pastry and bake, loosely covered with a sheet of foil, until filling is bubbling in center and crust is golden, about 1 3/4 hours.
• Transfer cake in pan to a rack and cool, uncovered, 20 minutes, then carefully remove side of pan.
• Cool cake to barely warm or room temperature, then cut into thick wedges with a sharp knife before serving.