Blueberry Peach Slab Pie

From the kitchen of Carly

A buttery slab pie loaded with peak-season peaches and blueberries, baked until the fruit softens into jammy pockets and the crust turns golden. This is the kind of dessert that feeds a crowd and tastes like summer in every bite.

Blueberry Peach Slab Pie

A slab pie feeds a crowd without fuss. Two separate butter doughs crisp up beautifully in a commercial sheet pan, cradling peak-season blueberries and soft peaches. The trick is keeping your butter cold and your water ice, so the pastry shatters rather than compresses. Build two crusts at once, chill them hard, and you're halfway there.

Prep
n/a
Cook
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Total
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Servings
4
Difficulty
medium

Ingredients

4 servings

  • 5 cupall-purpose flour, divided, plus more for rolling out dough
  • 2 1/2 tspsalt, divided
  • 11 1/4 cup plus 3 tablespoons granulated sugar, divided
  • 4 stickunsalted butter, cut into pieces, divided into 2 bowls, and frozen 15 minutes, plus more for baking sheet
  • 1 largeegg
  • 1 tbspwhole milk
  • 3 lbyellow peaches
  • 4 pintblueberries
  • 1/2 cupcornstarch
  • 2 tbspvanilla extract
  • 3 tbsplemon juice
  • 1 tbspsanding sugar or sugar in the raw
  • 213x18-inch rimmed baking sheets

Instructions

  1. Pour 2 1/2 cups flour, 1 teaspoon salt, and 1 1/2 tablespoons sugar into a food processor and pulse to combine. Add half the butter and pulse until the mixture looks like coarse, pea-sized crumbs. With the machine running, stream in 1/4 cup ice water and process until the dough just holds together. Pinch a small amount between your fingers; if it crumbles apart, drizzle in more ice water 1 tablespoon at a time, up to 2 tablespoons maximum. Stop as soon as it coheres.

  2. Turn the dough out onto a lightly floured surface and press it into a rough ball, kneading a few times until it comes together. Flatten into a disc, wrap in plastic, and refrigerate at least 1 hour or overnight. Run through the exact same process with the remaining 2 1/2 cups flour, 1 teaspoon salt, 1 1/2 tablespoons sugar, and butter to form a second disc. Wrap and refrigerate that one for at least 1 hour or overnight as well.

  3. Position one oven rack on the bottom rung and a second in the center, then heat the oven to 425°F. Line the bottom rack completely with foil to catch any drips, and set one 13x18-inch rimmed baking sheet on top of the foil so it preheats along with the oven.

  4. Butter a second 13x18-inch rimmed baking sheet. On a floured surface, roll one dough disc into a 14x19-inch rectangle about 1/8-inch thick. Drape the dough over your rolling pin and unfurl it onto the greased sheet, pressing it into the base and up over the rimmed edge; trim flush with the rim. Slide it into the refrigerator for 30 minutes. Roll the second disc to the same dimensions, transfer it to a large cutting board or two pieces of parchment taped together, and refrigerate that one for 30 minutes as well.

  5. Whisk the egg and milk together in a small bowl to make an egg wash and set it aside. Bring a large pot of water to a boil and fill a large bowl with ice water. Score the bottom of each peach with a shallow "x" using a paring knife, then drop them into the boiling water for 1 to 2 minutes until the skins loosen. Transfer to the ice bath, and once they are cool enough to handle, peel away the skins and slice the peaches into 1/2-inch thick wedges. Combine the peach wedges and blueberries in a large bowl with the remaining 1/2 teaspoon salt, 1 1/4 cups sugar, cornstarch, vanilla, and lemon juice. Toss well, then spread the fruit mixture evenly into the dough-lined baking sheet.

  6. Brush the outer edge of the filled crust with egg wash, then lay the second dough rectangle on top. Press the two crusts firmly together and trim the top layer flush with the rimmed edge. Tuck and fold the edges down into the base of the pan, crimping or decorating as you like. Coat the top crust with egg wash, scatter sanding sugar generously over the surface, and cut several vents into the crust with a paring knife to let steam escape.

  7. Slide the filled baking sheet onto the preheated sheet and bake on the bottom rack until the crust starts to turn golden, about 25 minutes. Rotate the stacked sheets, move them up to the center rack, and drop the oven temperature to 350°F, leaving the foil in place on the bottom rack. Continue baking, rotating the sheets once more halfway through, until the crust is deep golden brown and the juices are visibly bubbling and thickened, 60 to 70 minutes more. If the crust threatens to darken before the juices bubble, tent it loosely with foil. Transfer to a rack and cool at least 2 hours so the juices can set before slicing.

Tips from the kitchen

  • Keep all your ingredients and equipment cold, especially the butter and water. Pulse the dough in the food processor only until pea-sized crumbs form, then stop; overmixing kills flakiness.
  • If your peaches are not ripe enough to peel easily by hand after blanching, skip the blanch and use a vegetable peeler instead, or leave skins on for texture.
  • Assemble the filling just before building the pie so the fruit doesn't release too much liquid and make the bottom crust soggy.

Variations

  • Blueberry Plum Slab Pie, swap peaches for 3 pounds halved plums for a more tart, wine-dark filling.
  • Brown Butter and Sage Crust, brown 2 sticks of the butter with 4 to 5 fresh sage leaves, let cool, then chop the leaves fine and mix back into the dough for a savory edge.
  • Spiced Blueberry Slab Pie, add 1/2 teaspoon ground cardamom and 1/4 teaspoon ground clove to the filling for warmth without heavy spice.

Make ahead and storage

Store covered at room temperature for up to 2 days, or refrigerate up to 4 days. Freeze wrapped slices up to 3 months. Reheat gently in a 300°F oven to restore crust texture.