Apple crumble pie is the answer when you want both the clean slice of an apple pie and the craggy topping of an apple crisp. A single pastry shell holds the apples, and a handful of rolled oats gives the buttery topping a little more bite. The filling gets its flavor from the fruit, lemon and cinnamon, so the brown sugar on top can do its own job without making the whole pie taste the same.

Table of Contents

Ingredients

Use a 9-inch (23 cm) pie plate. The weights below are the clearest guide when measuring flour, produce or butter.

1 unbaked 9-inch pie crust (about 225 g; all-butter or verified pork-free pastry)
850 g peeled and cored apples, about 7 cups thinly sliced
65 g granulated sugar (⅓ cup)
18 g cornstarch (about 2 tablespoons plus 1 teaspoon)
15 ml lemon juice (1 tablespoon)
2.5 g ground cinnamon (1 teaspoon)
1.5 g fine salt (¼ teaspoon), divided equally
90 g all-purpose flour (¾ cup)
45 g old-fashioned rolled oats (½ cup)
75 g light brown sugar (⅓ cup packed)
85 g unsalted butter (6 tablespoons), cold and diced

How to make apple crumble pie

1. Line the pie plate and coat the apples

Heat the oven to 425°F (220°C) with a rack in the lower middle. Preheat a rimmed baking sheet if using a metal pie plate; use a room-temperature sheet if using glass. Fit the crust into a 9-inch (23 cm) pie plate without stretching it. Tuck and crimp the edge; chill while you work. Slice the apples about ¼ inch (6 mm) thick. Toss with the granulated sugar, cornstarch, lemon juice, cinnamon and half the salt until no dry starch remains.

Sliced apples tossed with cinnamon and sugar beside an unbaked pie shell

2. Fill the crust and add the oat crumble

Combine the flour, oats, brown sugar and remaining salt. Rub in the cold diced butter until no loose flour remains and the mixture forms rough clumps when squeezed. Layer the apples and any juice into the cold shell, putting slightly more fruit in the center. Scatter the oat crumble all the way to the edge without packing it down.

Oat crumble scattered over apple filling in a pastry crust

3. Bake until the center bubbles, then cool

Set the pie on the baking sheet. Bake 15 minutes, then reduce to 375°F (190°C) and bake another 40–45 minutes, until the filling bubbles through the topping near the center and the apples feel tender when pierced. Shield the crust or tent the top with foil if it browns early. Cool on a rack for at least 3 hours before slicing.

Baked apple crumble pie cooling on a wire rack

What makes the filling slice cleanly

Even slices are more useful than a particular variety. If some pieces are much thicker than others, the thin slices can collapse before the thick ones soften. A mix of tart Granny Smith and firm Pink Lady apples gives you a bright filling with a little natural sweetness. If you use all Granny Smith, expect a tarter slice; with all Pink Lady, expect a sweeter filling. Weigh the fruit after trimming it. The number of apples changes with their size, and that difference matters more than whether you peeled six or eight.

Toss the cornstarch with the sugar before you add them if yours tends to clump. The sugar separates the fine starch grains so they spread over the fruit instead of collecting in little white pockets. Use all the juice left in the bowl: it carries the starch and spice as well as the sugar. When loading the crust, turn the slices to fill obvious gaps. Loosely piled chunks settle more dramatically than neat layers.

How to get a crisp crumb topping

Old-fashioned rolled oats keep a distinct texture after baking. Quick oats will work in the same weight, though the crumble will look finer. Steel-cut oats stay too hard in the time this pie spends in the oven. Break up any hard lumps in the brown sugar before adding the butter. A mix of small crumbs and larger clumps browns more attractively than a perfectly uniform powder.

Stop mixing as soon as a squeezed handful holds together. The clumps should break easily between your fingers. If the bowl starts to feel greasy or the butter melts into a paste, put it in the refrigerator until it firms up. Scatter the cold clumps loosely over the fruit. Pressing them down makes an unbroken layer that tends to soften against the apples.

Troubleshooting the crust and the bake

A metal pie plate transfers heat to the bottom crust quickly; a glass pie plate lets you see the color underneath. If your glass plate manufacturer cautions against a preheated baking sheet or a sudden temperature change, use a room-temperature sheet with the glass dish, or use metal for the hot-sheet method. Avoid a dark sheet if your oven runs hot on the bottom.

Look for bubbles toward the middle, not just around the outer edge. The rim heats faster, and bubbling there can make an underdone pie look ready. An instant visual check is to part a little crumb with a thin knife near the center. The filling should look glossy and thickened, and the knife should slide into an apple slice with little resistance. If the top is already brown, tent it loosely and give the filling more time. The cooling period is part of the recipe; a hot pie may taste lovely but will be harder to cut cleanly.

Serving and storage

Serve at room temperature for the neatest wedges. A thin serrated knife helps cut through the crumb without dragging it across the plate. For a softer, warmer slice, reheat individual wedges in a 325°F (165°C) oven until warmed through. Keep the pie uncovered while reheating so steam can escape. Vanilla ice cream or unsweetened whipped cream is optional; neither is included in the nutrition estimate.

Refrigerate cooled leftovers, covered, for up to 3 days. If you want to freeze the pie, freeze the cooled slices separately so you can thaw only what you need. Wrap them well once firm and use within 2 months for best texture. Thaw in the refrigerator, then warm in the oven to help crisp the topping again.

FAQs

Can I use a frozen crust? Yes. Use an unbaked 9-inch shell and follow its packaging for thawing or handling. If it comes in a shallow disposable tin, use a deeper crust rather than forcing in the full weight of fruit.

Can I bake apple crumble pie a day ahead? Yes. Let it cool fully before covering and refrigerating. A brief oven warm-up revives the crumb, but let it settle again before cutting if you want especially tidy slices.

What if the topping is dry before it goes on? Keep rubbing the butter into the flour mixture a little longer. A few firm squeezes should produce clumps; adding water would make the flour sticky and change how the top bakes.

Conclusion

Make this cinnamon apple crumble pie with oat topping when you want a holiday dessert you can slice before guests sit down. The three things to watch are even apple slices, bubbles near the center and a full cool on the rack. Everything else, from the apple mix to the scoop on top, can suit your table.

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