This Triple Berry Slab Pie, made with fresh strawberries, blueberries, and blackberries, is a delicious way to feed a crowd at any backyard cookout, block party, or potluck! The super flaky all-butter crust is the star of the show, but the gooey berry filling shines with every bite!
Preheat oven to 375 degrees F. Lightly flour a work surface and roll out 2/3 of the triple batch of pie dough into a large 1/8th inch thick rectangle (about 18x13 inches in diameter). Trim excess dough and set aside. Press the rectangle into a 15x10 inch rimmed jelly roll pan or baking sheet, allowing the dough to hang over the edges slightly. Chill and prepare filling.
In a large mixing bowl, stir together berries, sugar, cornstarch, lemon juice, and salt. Pour mixture over chilled pie crust and spread evenly. Chill.
Re-flour your work surface and roll out the remaining piece of dough into a 16x11 inch rectangle, using the scraps from the base if necessary. Use a small shaped cookie cutter to cut random shapes in the top.
Carefully transfer the dough to the chilled pie and drape over filling. Fold hanging edges of dough over the top layer of dough. Prick the dough all over with a fork. Brush the surface of the pie evenly with heavy cream, then sprinkle with turbinado sugar.
Bake 45-55 minutes, or until crust is golden brown and filling is bubbling. Remove from oven and allow to cool on a wire rack at least 45 minutes before serving.
Notes
Recipe adapted from Food52.Slab pie is best served the day it's made. Cover any leftovers loosely with plastic wrap and store at room temperature for 2-3 days.