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This apple crisp with oatmeal has a thick, jammy apple layer and a topping that’s mostly oats, baked into crunchy golden clusters. It’s gluten-free too, and you don’t need a special flour blend, because the flour in the topping is just oats blended into powder!
I make this for my family in the morning, and yes, we eat it for breakfast like a dessert. It always finds its place on our table. My husband loves it so much!
So this apple crisp with oatmeal uses oats two ways. Whole rolled oats give you the crunch, ground oats hold everything together, and melted butter with brown sugar turns it all into clumps instead of dry sand. I’ve made it, and it’s the version I’m sticking with.
Why this apple crisp with oatmeal works
This recipe uses a lot of oats. Some versions use only half a cup, which gives you a thin, sugary crumble. This apple crisp with oatmeal has almost 2 cups of oats in total (counting the ones you grind), so the topping is thick and actually tastes like oats.
The apple layer is generous too. Six medium apples, about 2 pounds, fill an 8×8-inch pan properly, so every spoonful has as much fruit as crunch.
And one tablespoon of cornstarch goes in with the apples. Apples let out a lot of juice as they bake, and without something to thicken it, you get a puddle under the topping. With it, the juice turns glossy and jammy.
That’s really it. No fancy ingredients.
Which oats to use for apple crisp with oatmeal
For apple crisp with oatmeal, use old-fashioned rolled oats. They’re big, flat flakes that hold their shape in the oven and turn crisp at the edges.
Quick oats are cut smaller, so they soak up the butter faster and bake into a softer, more cookie-like top. They work in a pinch.
Steel-cut oats don’t work here. They’re little chopped pieces of whole oat that need to simmer in liquid, and in a dry topping they stay hard.
What about instant oatmeal packets? I’d skip them. Most are already sweetened and flavored, and the oats are cut so thin they go pasty instead of crunchy. (I go deeper into rolled, quick, and steel-cut oats in my peanut butter oatmeal cookies post.)
Making sure your oats are gluten-free
Oats don’t contain gluten on their own, but regular oats are often grown and processed alongside wheat, barley, and rye, so they pick some up along the way. Buy oats labeled certified gluten-free, and use the same oats for your oat flour.
If you’re baking for someone with celiac disease, you might choose purity protocol oats, which are grown and processed separately from start to finish. Most people with celiac can eat pure oats, but a small number react to the protein in oats themselves (it’s called avenin). The Celiac Disease Foundation has a good, plain explanation of gluten-free oats if you want to read more. If you’re not sure, ask before you bake.
Ingredients for apple crisp with oatmeal
Apples: Pick firm baking apples that hold their shape, like Granny Smith, Honeycrisp, Pink Lady, or Braeburn. A mix of tart and sweet tastes best to me. Soft apples like McIntosh break down into applesauce in the oven. I use Granny Smith and Honeycrisp together. The Granny Smith keeps the filling a little tangy, and the Honeycrisp makes it sweet and juicy.
Lemon juice: Wakes up the apple flavor and keeps the slices from browning while you work.
Cornstarch: This is what makes the filling jammy instead of watery. Arrowroot powder works the same way if you avoid corn.
Sugar for the apples: Just 3 tablespoons, granulated or light brown. If your apples are very sweet, 2 is plenty.
Oat flour: Blend about ⅔ cup of rolled oats for 30 seconds or so, until it looks like fine powder. Then measure out ½ cup. Store-bought certified gluten-free oat flour works too. If you end up loving homemade oat flour, I use a toasted version of it in my fudgy gluten-free brownies.
Brown sugar: Packed. Its moisture is a big part of why the topping clumps, and it tastes a little like caramel once baked.
Butter: Unsalted and melted. If you only have salted, cut the salt down to a pinch.
Salt: Only ¼ teaspoon, but leave it out and the topping tastes flat and too sweet.
Melted butter or cold butter?
Melted, especially for apple crisp with oatmeal. When you pour melted butter over the oats and brown sugar, it coats every flake and mixes with the brown sugar into a sticky paste. That paste is what bakes into crunchy clusters.
Cold butter cut into cubes and rubbed in with your fingers gives you a sandier, crumblier top, more like streusel. It’s nice, just different. It’s also more work, since you need a pastry cutter or your fingertips, and the butter has to stay cold.
So if you love big crunchy clumps, go melted. If you like a fine crumble, cold butter is your friend.
How to make apple crisp with oatmeal
The full steps for this apple crisp with oatmeal are in the recipe card below, but these are the parts that matter most.
Slice the apples about ¼ inch thick. Thicker slices can stay crunchy in the middle, and thinner ones go mushy. Toss them with the sugar, lemon juice, cinnamon, and cornstarch until you can’t see any white powder, then pour everything into the pan, juices too.
For the topping, stir the dry ingredients first, then pour in the melted butter and mix with a fork. You’re looking for something like wet sand with lots of pea-sized clumps. Squeeze a handful. If it holds together, it’s ready.
Scatter it over the apples and don’t press it down! A loose, bumpy surface is what gets crunchy.
Bake at 350°F for 40 to 50 minutes. It’s done when the topping is deep golden and the juices bubble up thickly around the edges. That bubbling matters, because cornstarch needs to boil before it fully thickens. Then slide a knife through the topping into the apples. It should go in with no resistance.
[Photo: baked crisp with juices bubbling at the edges of the pan]
Now the hard part. Let your apple crisp with oatmeal rest for 15 minutes so the filling can set.
Tips for apple crisp with oatmeal
Why is my apple crisp watery? Usually it was cut too soon, or it came out of the oven before the juices were bubbling thickly. Skipping the cornstarch does it too. If it happens, don’t worry. Leftovers firm up a lot in the fridge overnight.
Topping soft or pale? It was probably pressed down, or it needed a few more minutes. Put the pan back in for 5 to 10 minutes. Quick oats also give a softer top than rolled oats.
Topping browning before the apples are tender? Lay a piece of foil loosely over the pan for the last 10 to 15 minutes. It slows the browning while the apples keep cooking.
Apples still firm? The slices were likely a bit thick, or your apples are very firm. Cover with foil and give it another 10 minutes.
Variations and substitutions
Add nuts: Stir ½ cup chopped pecans or walnuts into the topping before the butter goes in. For a nut-free crunch, use ⅓ cup pumpkin seeds.
Dairy-free: To make dairy-free apple crisp with oatmeal, swap the butter for 6 tablespoons of melted coconut oil or vegan butter. Refined coconut oil tastes neutral, while unrefined adds a little coconut flavor.
With an oat bottom layer: Some people love their apple crisp with oatmeal on the bottom too. Make a double batch of topping, press about a third of it firmly into the greased pan, add the apples, then scatter the rest on top. The bottom layer bakes up soft and chewy, a bit like an oat bar, not crunchy. Expect a few extra minutes in the oven.
For a crowd: Double everything and bake in a 9×13-inch pan for 50 to 60 minutes, until it’s bubbling thickly at the edges.
Apples and pears: Swap 2 of the apples for firm pears. Pears are juicier, so add an extra ½ tablespoon of cornstarch.
Less refined sugar in the filling: Use 2 tablespoons of pure maple syrup instead of the sugar in the apples.
How to serve apple crisp with oatmeal
Warm apple crisp with oatmeal, with a scoop of vanilla ice cream melting into the oats, is the classic for a reason. Softly whipped cream is lovely too, and a drizzle of caramel sauce never hurts (check the label to make sure it’s gluten-free).
I’ve tried it every way: with ice cream, with whipped cream, warm from the oven, and cold from the fridge the next day. Honestly, they’re all good! At our house, though, it’s mostly a breakfast thing.
If you want to try it for breakfast too, spoon a warm or cold square over plain or vanilla Greek yogurt. For a slow weekend morning, serve it next to a stack of fluffy gluten-free pancakes.
Storage, make-ahead, and reheating
Storing: Cover your apple crisp with oatmeal and keep it at room temperature for up to 1 day, or in the fridge for up to 4 days.
Reheating: The oven is the way to go if you want the crunch back. Warm leftover apple crisp with oatmeal in an oven-safe dish at 350°F for 10 to 15 minutes. An air fryer works for a single serving in a small dish, about 5 minutes at 320°F. The microwave is fastest, but the topping turns soft.
Making it ahead: Mix the topping and keep it in a container in the fridge for up to 3 days, or in a freezer bag for up to 3 months. Slice the apples right before baking (they brown if they sit), then scatter the topping straight from the fridge or freezer. From frozen, add about 5 minutes.
Can you freeze baked apple crisp with oatmeal? You can, for up to 2 months. Thaw it in the fridge overnight and rewarm it in the oven. The topping won’t be quite as crunchy, which is why I’d rather freeze the topping on its own.
Apple crisp with oatmeal FAQs
Do I have to peel the apples?
No. The peels stay a little chewy and curl up as they bake. I peel mine for a softer filling, but leaving them on saves about 10 minutes.
Can I skip the oat flour?
You can swap it for ½ cup of a 1:1 gluten-free flour blend. Almond flour works too, but the topping gets richer, more crumbly, and browns faster, so keep an eye on it. With no flour at all, the topping bakes up loose, like granola, instead of in clusters.
Can I use less sugar?
In the apples, yes, down to 1 or 2 tablespoons with sweet apples. In the topping, you can go down to ⅓ cup brown sugar. Expect fewer clumps, since the sugar is part of what holds them together.
What’s the difference between apple crisp and apple crumble?
They’re very close. In the US, a crisp usually has oats in the topping, and a crumble is often a streusel of flour, sugar, and butter without oats. Plenty of people use the names for the same thing, though.
More gluten-free desserts to try
Still have apples left? The apple hand pies and turnovers in my gluten-free puff pastry guide are a good next bake. For more cozy fall baking, try my gluten-free carrot cake, or browse these 13 easy gluten-free dessert recipes and all my gluten-free desserts.
If you make this apple crisp with oatmeal, I’d love to know which apples you used! Leave a rating in the recipe card, and tell me in the comments if you tried the oat bottom layer.
