The next time you need a dessert for a crowd—backyard barbecue, picnic, block party, or potluck—think slab pie. This version pairs juicy peaches with heady vanilla bean; we opt for vanilla bean paste, but you can also use an equal amount of vanilla extract. You’ll need to patiently work with the dough to roll it out large enough to cover the pan. Don’t worry about overworking it; it’s so thin that it can’t get tough.
1/2 cup cold unsalted butter, cut into small pieces
1/4 cup olive oil
1 tablespoon fresh lemon juice
2/3 cup plus 1 to 2 Tbsp. cold water, divided
6 pounds ripe peaches, peeled and sliced (about 12 cups)
1 1/3 cups packed brown sugar
3 tablespoons cornstarch
1 tablespoon vanilla bean paste or vanilla extract
1 teaspoon ground cinnamon
1 large egg yolk, lightly beaten
1 teaspoon room-temperature water
Est. added sugars 16g
How to Make It
Pulse flours and 1 teaspoon salt in a food processor 2 times. Add butter; pulse until mixture resembles coarse meal, 4 to 5 times. Stir together oil, lemon juice, and 2/3 cup cold water in a small bowl. While pulsing, pour oil mixture through food chute. Process just until dough comes together and starts to form a shaggy ball. Add an additional 2 tablespoons cold water, 1 tablespoon at a time, if necessary to bring dough together. (Be careful not to overprocess.)
Turn dough out onto a work surface; knead until dough just comes together, about 2 times. Divide dough into 2 pieces, one roughly 60% of the dough and the other 40%. Flatten each into a 1-inch-thick disk; wrap each in plastic wrap. Chill 2 hours or up to overnight.
Preheat oven to 375°F. Combine peaches, brown sugar, cornstarch, vanilla bean paste, cinnamon, and remaining 1/4 teaspoon salt in a large bowl; toss well to combine. Set aside.
Remove dough disks from refrigerator, and unwrap. Place larger dough disk between 2 lightly floured sheets of plastic wrap; roll into a very thin 20- x 15-inch rectangle. Using a thin pan or cutting board for support, carefully slide dough from plastic wrap onto a 13- x 18-inch rimmed baking sheet. Remove plastic wrap, and press dough into corners of baking sheet. Spoon peach mixture evenly over dough. Place second dough disk between 2 lightly floured sheets of plastic wrap; roll into a very thin 13- x 18-inch rectangle. Cut dough lengthwise into 3/4-inch-thick strips. Arrange strips in a lattice pattern over peach mixture; crimp edges to seal. Whisk together egg yolk and 1 teaspoon room-temperature water in a small bowl. Brush dough lattice evenly with egg yolk mixture.
Bake at 375°F until filling is thick and bubbly and crust is browned, about 50 to 55 minutes. Cool at least 20 minutes before serving.