This apple crumble slab pie has been my go-to for autumn gatherings and holiday potlucks since I first tested it on a rainy October afternoon. I fell in love with the idea of taking everything I adore about a classic apple pie—the tender, cinnamon-scented apples and the buttery crust—and turning it into a rustic sheet-pan version that serves a crowd with zero fiddly lattice work. The result is familiar and comfortingly nostalgic, but easier to assemble and reliably beautiful every time.

I discovered this olive-branch-to-busy-bakers technique while planning a family reunion; I needed something that would bake evenly in a single tray and slice into generous bars. The thick apple filling becomes syrupy from reduced apple cider, the crust bakes flaky without being fragile, and the oat crumble on top adds the exact amount of crunch and chew that keeps everyone reaching for seconds. Serve warm with a scoop of vanilla ice cream and watch the room melt into contented silence.

Ingredients

• Pie crust: Use cold unsalted butter for a flaky crust—I prefer Plugrá or Land O Lakes when available. Cold butter cut into flour creates steam pockets during baking, producing that lift and flake you want. Buttermilk adds a touch of acidity and tenderness; substitute with 1/2 tablespoon distilled white vinegar plus 1/2 cup milk if needed.
• Apple filling: Choose firm, tart-sweet apples that hold their shape—Honeycrisp, Fuji, or a mix of Granny Smith and Gala. Apple cider reduced to a syrup brings concentrated fruit flavor; measure 1/2 cup before reducing. The double-thickening with flour and cornstarch prevents a runny filling.
• Crumble topping: Rolled old-fashioned oats add chew while cold butter makes the crumble clump and crisp up during baking. Use light or dark brown sugar for depth; the crumble spices should echo the filling to create a cohesive flavor.
• Spices & salt: Cinnamon, nutmeg, allspice, and a pinch of cloves form a warm spice blend—measure carefully and taste as you build flavors. Salt balances sweetness and boosts aroma; use fine sea salt for even distribution.

Instructions

Prepare the dough:In the bowl of a food processor, pulse 2 1/2 cups all-purpose flour, 1 tablespoon sugar, 1 teaspoon salt, and 1 cup (2 sticks) cold unsalted butter cut into cubes until the mixture resembles coarse sand with pea-sized bits of butter. Add 1/2 cup cold buttermilk and pulse just until a dough starts to come together and clumps form. Don’t over-process; you want visible butter flakes. Turn the dough onto a lightly floured surface, shape into a 7-8 inch flat square, wrap in plastic, and chill for 30 minutes while you make the filling and crumble.Make the filling:Bring 1/2 cup apple cider to a boil in a medium saucepan over medium heat and reduce until syrupy, about 3–5 minutes. Add 8 cups peeled, cored, and sliced apples (about 8 medium apples), 2 tablespoons lemon juice, 2 tablespoons unsalted butter, 2/3 cup sugar, 2 tablespoons all-purpose flour, 2 tablespoons cornstarch, 1 teaspoon cinnamon, 1/4 teaspoon nutmeg, 1/4 teaspoon allspice, and 1/4 teaspoon salt. Cook, stirring occasionally, until apples release juices and the mixture thickens, about 5–7 minutes. Remove from heat and let cool slightly so it’s easier to assemble.Make the crumble:In the food processor (no need to rinse), pulse 1 cup all-purpose flour, 1/2 cup brown sugar, 1/2 cup granulated sugar, and 1/2 cup (1 stick) cold unsalted butter until crumbly. Transfer to a bowl and stir in 1 cup rolled oats, 1 teaspoon cinnamon, 1/2 teaspoon nutmeg, 1/4 teaspoon allspice, a pinch of ground cloves, and a pinch of salt. The mixture should hold together when pressed but still be loose enough to scatter over the apples.Assemble the slab:Preheat the oven to 375°F. On a lightly floured surface, roll the chilled dough to an 18 by 13-inch rectangle. Fold into quarters to transfer, then unfold it into a 15 by 10-inch rimmed jelly-roll pan, pressing to the edges and up the sides. Pour the apple filling evenly into the crust and scatter the crumble topping across the surface, aiming for full coverage.Bake and finish:Bake for 45–50 minutes until the crumble and crust are golden brown and the filling is bubbling at the center. If the edges brown too quickly, tent loosely with foil. Let cool to room temperature before slicing into 16 bars; serve warm with vanilla ice cream or lightly whipped cream.

Storage Tips

Store covered at room temperature for up to 48 hours for the best texture; beyond that, refrigerate in an airtight container for up to 5 days. When refrigerating, place a sheet of parchment between layers to prevent sticking. To reheat, warm individual slices in a 325°F oven for 8–12 minutes or microwave for 20–30 seconds—if frozen, thaw in the refrigerator overnight and reheat in the oven for best crumble texture. For longer storage, wrap tightly in plastic, then foil, and freeze for up to 3 months. Reheat from frozen at 350°F for 15–20 minutes, tenting with foil if top browns too fast.

Ingredient Substitutions

If you don’t have buttermilk, substitute 1/2 tablespoon white vinegar stirred into 1/2 cup milk and let sit for 5 minutes. For a dairy-free version, use a vegan butter substitute measured stick-for-stick and a plant-based milk for the buttermilk swap; note that flavor and flakiness will be slightly different. Swap cornstarch for arrowroot powder at a 1:1 ratio for a clear, glossy filling. If you prefer a nutty crumble, replace 1/2 cup of the oats with chopped toasted pecans or walnuts—this adds flavor and crunch but slightly changes the bake time for perfect browning.

Serving Suggestions

Serve warm with good-quality vanilla ice cream or a dollop of lightly sweetened whipped cream. For a brunch twist, cut into smaller squares and offer alongside coffee and cinnamon lattes. Garnish with toasted oats or a light dusting of powdered sugar for a pretty finish. For an elegant dinner, plate a warm slice with a quenelle of crème fraîche and a drizzle of caramel sauce, or keep it casual on picnic plates with paper napkins and forks—either way, it’s a crowd-pleaser.

Cultural Background

Sheet-pan pies are a modern, practical spin on traditional fruit pies that have been part of American home baking for centuries. The crumble topping has roots in British and New England cooking where oats and brown sugar were common pantry staples; combining a buttery pie base with a streusel creates a hybrid that honors both pastry and cobbler traditions. This slab format evolved from the need to serve larger groups efficiently while maintaining the comforting flavors of apple desserts that are central to fall harvest celebrations.

Seasonal Adaptations

In fall, use a mix of Honeycrisp and Granny Smith for a balance of sweetness and tartness. Winter calls for adding a splash of brandy or bourbon to the filling for warmth. In late summer, swap apples for stone fruits like peaches or plums with slightly less lemon juice and a pinch more cornstarch to account for juicier fruit. Holiday versions can include chopped crystallized ginger in the filling or a scatter of pepitas on the crumble for festive texture and flavor.

Meal Prep Tips

Make the dough and crumble topping the day before and keep them chilled separately. Prepare the apple filling three hours ahead and refrigerate; if the filling firms up, warm gently before assembling. When ready to bake, roll out chilled dough directly into the pan, add the filling, top with crumble, and bake. This split-prep approach reduces day-of stress and keeps flavors bright. Use shallow rimmed pans for even baking and set a baking sheet on the rack below to catch any drips during the first 20 minutes.

There’s something deeply satisfying about serving this slab and watching people gather—its generous format invites conversation and seconds. Make it your own with apple varieties and spice levels you love, and don’t be afraid to bake it for guests; the reward is always a full table and happy faces.