2 1/2 pounds (about 6 cups) fresh mixed berries,
such as blackberries, blueberries, and raspberries
1 1/4 cups granulated sugar
1/4 cup cornstarch
Juice of 1/2 lemon (about 1 tablespoon)
1/4 teaspoon salt
2 tablespoons heavy cream
1/4 cup sanding sugar
1. Preheat oven to 375F. On a lightly floured surface, roll out larger piece of dough to an 18-by-13-inch rectangle.
Fit into a 15-by-10-inch rimmed baking sheet, pressing into corners (pastry will hang over sides). Chill while assembling filling.
2. In a large bowl, stir together berries, granulated sugar, cornstarch, lemon juice, and salt. Spread mixture over chilled pie shell.
3. On a lightly floured surface, roll out remaining piece of dough to a 16-by-11-inch rectangle; drape over filling. Fold edge of bottom dough over top dough. Pinch edges to seal. Prick top dough all over with a fork. Brush entire surface of pie with cream, and sprinkle with sanding sugar.
4. Bake until crust is golden brown and filling is bubbling, 40 to 55 minutes. Transfer to a wire rack, and let pie cool until it is just warm to the touch, about 45 minutes. Serve warm or at room temperature, cut into 12 pieces. Slab pie is best eaten the same day it is baked, but it can be kept at room temperature, loosely covered with plastic wrap, for up to 2 days.
Slab Pie Pate Brisee
Makes enough for one 15-by-10-inch pie
3 3/4 cups all-purpose flour
2 1/2 teaspoons coarse salt
1 1/2 teaspoons sugar
1 1/2 cups (3 sticks) unsalted butter, cold, cut into small pieces
1/2 cup ice water, plus more if needed
1. Place flour, salt, and sugar in the bowl of a food processor; pulse for a few seconds to combine. Add butter; pulse until mixture resembles coarse crumbs, about 10 seconds.
2. With machine running, pour ice water through feed tube in a slow, steady stream, until dough just holds together when squeezed. If needed, add more ice water 1 tablespoon at a time. Do not process for more than 30 seconds.
3. Turn out dough onto a clean work surface. Divide into two pieces, one slightly larger than the other. Form into flattened rectangles. Wrap each in plastic, and refrigerate for at least 1 hour or up to overnight.