Apple Blackberry Crisp with Crunchy Oat Walnut Topping
Sweet apples, juicy blackberries and the chunky oat-walnut topping I make when I want plenty of crunch without an overly sweet dessert. This version keeps the fruit at the center, with maple sugar for sweetness and an oat-walnut topping that adds plenty of texture without burying the berries under a thick layer of sugar and flour.
This apple blackberry crisp combines tender apple chunks with juicy, slightly tart blackberries under a golden topping made with rolled oats, walnuts and cold butter. The fruit becomes soft and jammy without turning watery, while the topping stays chunky and crisp around the edges. Fresh or frozen blackberries both work, and the recipe can easily be adapted gluten-free or dairy-free without changing the basic texture.
Why This Apple Blackberry Crisp Works
Apples and blackberries behave very differently in the oven, which is exactly why they work so well together.
- Apples give the filling structure while the blackberries soften and create a juicy, jammy sauce.
- Arrowroot catches the berry juices so the bottom doesn’t become watery.
- Rolled oats + walnuts create real crunch rather than a soft flour-only topping.
- Very cold butter creates uneven clusters that stay crisp as they bake.
- Maple sugar adds gentle caramel flavor without making the filling excessively sweet.
- Fresh or frozen blackberries work, making this an easy dessert beyond berry season.
The finished crisp has a nice contrast: tender fruit underneath and larger crunchy oat-walnut pieces on top.
Why I Use These Ingredients
Apples + Blackberries
- Apples provide the firmer base of the filling, while blackberries add tartness, deeper berry flavor and plenty of juice.
- I like apples that hold their shape while baking, such as Honeycrisp, Gala, Fuji, Cortland or Empire. Using both a sweet and a slightly tart apple gives the filling even more depth.
- Fresh blackberries are wonderful in season, but frozen berries work very well too.
- Best berry swaps: raspberries or blueberries can replace the blackberries, although the flavor and amount of juice will change slightly.
Rolled oats + Walnuts
- Old-fashioned rolled oats create the coarse, crisp texture I want here. Walnuts add another level of crunch and a slightly toasted flavor that pairs particularly well with apples.
- Avoid steel-cut oats. Quick oats can work, but the topping will be finer and softer.
- For nut-free, omit the walnuts or replace them with pumpkin or sunflower seeds.
For more detail on controlling the size of the crumbs, see my healthy oat crumble topping recipe.
Flour + Cold Butter + Arrowroot
- A small amount of flour coats the butter and helps the topping form clusters rather than simply melting into the fruit.
- The temperature of the butter matters. I freeze it before mixing because those small cold pieces create more defined crumbs as they bake.
- For gluten-free, use a dependable 1:1 gluten-free flour blend and certified gluten-free rolled oats.
- For dairy-free, a firm plant-based butter like Miyoko’s for the closest texture to regular butter.
- Blackberries release quite a bit of juice as they cook. Arrowroot thickens that liquid into a light fruit sauce rather than letting it pool at the bottom of the dish. Cornstarch can be a substitute.
Maple Sugar + Warm Spices
- Maple sugar adds mild caramel notes that work especially well with apples, walnuts and cinnamon. Coconut sugar or brown sugar can also be used.
- Cinnamon and a little nutmeg or cardamom are enough here, I prefer the fruit to stay the main flavor.
How to Make Apple Blackberry Crisp
1. Prepare the fruit
- Preheat the oven to 360°F (182°C).
- Cut the apples into small, fairly even chunks and place them in a 9-inch square pan. Squeeze some lemon juice over (optional).
- Add the blackberries, maple sugar, arrowroot and cinnamon. Toss gently until the fruit is evenly coated, then spread everything into an even layer.
- If you’re using fresh blackberries, rinse and dry them first. Frozen blackberries can go straight into the dish.
2. Make the oat-walnut topping
- Freeze the butter for at least 1 hour before starting.
- Add the cold butter and flour to a food processor and pulse briefly until you have coarse, uneven crumbs.
- Add the rolled oats, walnuts, maple sugar, cinnamon and nutmeg and mix just until combined.
- For larger crunchy clusters, let the mixture sit for a few minutes, then squeeze small handfuls together before scattering them over the fruit.
For step-by-step photos and a deeper insight into the technique, see my full oat crumble topping recipe.
3. Assemble
- Spread the topping loosely over the apple-blackberry filling.
- Don’t pack it down. Leaving plenty of uneven edges exposed helps it brown and crisp.
4. Bake
- Bake for about 35–38 minutes, until the topping is golden and the fruit is bubbling around the edges.
- Frozen blackberries may add a few minutes to the baking time.
5. Rest before serving
- Let the crisp cool for at least 15 minutes before serving.
- The blackberry juices will continue to thicken as the crisp rests.
- Serve warm on its own or with vanilla ice cream, dairy-free ice cream or plain yogurt.
Make In Advance Tip
The apple blackberry crumble can be made in advance and stored for up to 2 days in the fridge (just keep the fruits and topping in separate containers). If you’re planning to bake the same day, then there is not need to separate. Bake whenever you’re ready.
Is this an apple blackberry crisp or an apple blackberry crumble?
For an American audience, crisp is the more accurate name for this recipe because the topping contains rolled oats and is meant to bake crunchy.
In the UK, a very similar dessert is commonly called apple and blackberry crumble, and British crumble recipes often include oats as well. The terms overlap, but because this version has a distinctly crisp oat-and-walnut topping, I use apple blackberry crisp throughout the recipe.
Tips for the Best Apple Blackberry Crisp
If using frozen blackberries
Don’t thaw them first. Add the berries directly from the freezer so they release their liquid gradually during baking. Because frozen fruit lowers the temperature of the filling, the crisp may need a few extra minutes in the oven.
For a gluten-free crisp
Use certified gluten-free rolled oats and replace the ⅓ cup flour with the same amount of a reliable 1:1 gluten-free flour blend. I prefer using my gluten free flour mix over swapping in a single flour such as almond, rice or arrowroot because those absorb fat differently and can noticeably change the topping.
For dairy-free
Replace the butter 1:1 with a firm dairy-free butter like Miyoko’s and keep it very cold before mixing. Solid coconut oil can also work, although the topping tends to be finer and less buttery in texture.
If the filling looks watery
Wait before assuming something went wrong. The fruit filling is much looser straight from the oven. Make sure it has bubbled during baking, then let the crisp rest for 15–20 minutes so the arrowroot can finish thickening the juices.
For bigger oat-walnut clusters
Don’t over-process the butter and flour. Once everything is mixed, squeeze portions of the topping together with your fingers before adding them over the fruit. Those irregular clumps create the best crunchy pieces.
Optional add-ins: flaked coconut, dried fruits, crushed pecans or sliced almonds (or seeds if allergic to nuts).
If changing the pan size
A 9-inch square pan gives the best balance of fruit and topping. An 8-inch dish makes a deeper filling and may require a little more baking time. A larger, shallower dish cooks faster and creates more exposed topping, so start checking it earlier.
Smaller portions: bake the apple and blackberry crumble in small individual ramekins instead of one large pie dish.
Apple Blackberry Crisp FAQs
Yes. Frozen blackberries work very well. Don’t thaw them first. Add them directly to the filling and allow a few additional minutes of baking time if needed.
Choose an apple that won’t completely collapse while baking.
Honeycrisp, Gala, Fuji, Cortland and Empire all work well. For more contrast, combine a sweeter apple with a tart variety.
Blackberries naturally release a lot of juice. Use the full amount of arrowroot, bake until the filling is visibly bubbling, and allow the crisp to rest before serving. The juices thicken considerably as they cool.
Yes. Prepare the fruit filling and oat topping separately and refrigerate them for up to 2 days. Add the topping just before baking so it doesn’t absorb moisture from the fruit.
Cover and refrigerate baked crisp for up to 3 days.
To bring back some of the crunch, reheat it uncovered in the oven rather than the microwave.
Yes. You can freeze it baked or unbaked for up to 3 months, although freezing it before baking usually preserves the topping texture better.
Bake from frozen at 360°F and allow additional time as needed.
Before You Go…
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If you prefer blueberries with apples, my apple blueberry crisp with oats has a slightly sweeter, softer berry filling. When peaches are in season, this healthy peach crisp with oats uses the same general fruit-and-oat format.
Apple Blackberry Crisp with Oat Walnut Topping
Ingredients
Apple Blackberry Filling
- 3 large apples - cut into chunks
- 6-7 oz fresh blackberries
- 3 tbsp maple sugar - or your favorite
- 2 tbsp arrowroot flour - or any other starchy flour
- 1 tsp lemon juice - optional
- 1 tsp cinnamon - optional
Crunchy Oat Walnut Topping
- ¾ cup rolled oats - or use gluten free certified oats
- ⅓ cup flour - for gluten free see notes
- ½ cup crushed walnuts - or seeds if allergic to nuts
- 6 tbsp butter - cold (for dairy free see notes)
- ⅓ cup maple sugar - or your favorite granulated sugar
- ½ tsp cinnamon
- ⅕ tsp nutmeg - or cardamom
Instructions
- Chill the butter. Place the butter in the freezer for at least 1 hour before making the topping.
- Prepare the fruit. Preheat the oven to 360°F (182°C). Add the chopped apples and blackberries to a 9-inch square pan. Squeeze the lemon juice (optional) and sprinkle with maple sugar, arrowroot and cinnamon and toss gently until evenly coated. Spread the apple and blackberry filling in an even layer.
- Make the topping. Add the frozen butter and flour to a food processor and pulse briefly until coarse crumbs form. Add the rolled oats, walnuts, maple sugar, cinnamon and nutmeg and mix just until combined.
- Create larger clusters, if desired. Let the mixture sit at room temperature for 5–8 minutes, then gently squeeze portions together with your hands.
- Assemble. Scatter the oat-walnut topping loosely and evenly over the fruit.
- Bake. Bake for 35–38 minutes, or until the topping is golden and the blackberry juices are bubbling around the edges.
- Cool. Let the crisp rest for at least 15 minutes before serving so the fruit filling can thicken.
- Serve warm, at room temperature or chilled.
Notes
Nutrition
The information shown is an estimate provided by an online nutrition calculator.
More Healthy Fruit Desserts
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This has a perfect ratio of fruit and oat topping, it came out so good… Great flavor too… I don’t think blackberry alone would be that delicious, so the addition of apple is just right!
Glad you tried it!
Just loved it, the right texture – gooey not watery inside and crispy crumb..perfection 👌