Apple Plum Crisp with Oats & Walnuts
Juicy late-summer plums and tender apples under a crunchy oat-walnut topping – the kind of dessert I start making when summer begins to turn into fall.
This apple plum crisp combines sweet apples with soft, slightly tart plums and a golden topping made with rolled oats, walnuts and cold butter. The plums become almost jammy as they bake, while the apples hold more structure, giving the filling a better balance than using either fruit alone.
I think of this as a more wholesome take on a classic fruit crisp: there’s plenty of real fruit, rolled oats, walnuts and maple sugar instead of relying heavily on refined flour and sugar.
As a recipe developer and Integrative Nutrition Health Coach, that’s generally how I prefer to approach desserts. It’s still a sweet dessert (not diet food) but one made with wholesome ingredients that also bring fiber, texture and flavor.
Why This Apple Plum Crisp Works
Apples and plums soften at different rates, so a few small details make a noticeable difference here.
- Apples give the filling structure while the plums soften into a juicy, almost jammy layer.
- The apples are sliced thinner than the plums so both fruits finish cooking at roughly the same time.
- Arrowroot thickens the plum juices without making the filling heavy.
- Rolled oats and walnuts create plenty of crunch and keep the topping from feeling too flour-heavy.
- Very cold butter creates larger, irregular clusters instead of a fine sandy crumb.
- Maple sugar adds mild caramel flavor that works particularly well with apples, plums and warm spices.
The result is sweet, tart, juicy and crisp in the right places, without needing an overly thick layer of topping.
Why I Use These Ingredients
Apples + Plums+ Arrowroot
- This combination works because the two fruits bring different things to the filling.
- Apples stay relatively firm and naturally sweet, while ripe plums soften much more and provide acidity and juice.
- I use Gala apples, but Honeycrisp, Fuji, Pink Lady, Braeburn or a mixture of sweet and tart apples also work.
- For the plums, black, red, purple or yellow varieties are all fine. Choose fruit that is ripe enough to have good flavor but still firm enough to slice cleanly.
- I leave the plum skins on. They soften during baking, add color and help the plum pieces hold together.
- Plums release quite a bit of juice as they bake. Arrowroot helps turn that liquid into a light sauce around the fruit instead of leaving a watery layer at the bottom. Cornstarch is the easiest substitute.
Rolled Oats + Walnuts
- Old-fashioned rolled oats give this crisp its rustic texture, while walnuts add larger crunchy pieces and a slightly toasted flavor. Pecans are the closest substitute.
- If you need the recipe gluten-free, use certified gluten-free rolled oats.
- For more detail on making larger or finer crumbs, see my healthy oat crumble topping recipe.
Flour + Cold Butter
- A small amount of flour helps the butter form clusters around the oats rather than simply melting through the topping.
- For gluten-free, replace it with the same amount of a reliable 1:1 gluten-free flour blend. I used my gluten free all-purpose flour mix.
- I freeze the butter before mixing. Those small pieces melt gradually in the oven and create more defined, crunchy crumbs.
- For dairy-free, a firm plant-based butter gives the closest result. My best choice is this firm cultured plant milk butter.
Maple Sugar + Spices
- Maple sugar gives the crisp a mild caramel flavor without covering up the fruit.
- Brown sugar or coconut sugar also work.
- Cinnamon and cardamom are enough to give the filling and topping warmth without making the dessert taste overly spiced.
How to Make Apple Plum Crisp
1. Make the oat-walnut topping
- Freeze the butter for at least 1 hour.
- Grate the frozen butter into the flour and toss until coated, or pulse the butter and flour briefly in a food processor until coarse crumbs form.
- Add the rolled oats, walnuts, maple sugar, cinnamon and cardamom and mix just until combined.
- Keep the topping chilled while preparing the fruit.
2. Prepare the apples and plums
- Preheat the oven to 360°F (182°C).
- Core the apples and slice them fairly thin.
- Pit the plums and cut them into slightly thicker wedges. There is no need to peel them.
- Add both fruits to a 9-inch square baking dish (I used non-stick ceramic) and toss with the maple sugar, arrowroot, cinnamon and optional lemon juice.
- Spread into an even layer.
3. Add the topping
- Scatter the chilled oat-walnut mixture loosely over the fruit.
- Don’t press it down firmly. Leaving an uneven surface creates more exposed edges that can brown and become crisp.
4. Bake
- Bake for about 38–40 minutes, until the topping is golden and the fruit is visibly bubbling around the edges.
- If the topping begins browning too quickly, loosely cover the dish with foil during the last part of baking.
Tips For Best Results
✤ Slice the apples thinner than the plums. Apples take longer to soften, while ripe plums break down quickly. Different thicknesses help them reach the right texture at the same time.
✤ Choose ripe but still firm plums. Very soft plums can release a lot of liquid and disappear into the filling. Save those for sauces, smoothies or jam.
✤ Keep the plum skins on. They soften in the oven, add beautiful color and help the fruit retain some structure.
✤ Use lemon juice according to the fruit. If your plums are already quite tart, you may not need it. If they’re especially sweet, a little lemon brightens the filling.
✤ Look for bubbling fruit, not only a brown topping. The topping can look finished before the center is hot enough. Bubbling around several edges is a better sign that the fruit and arrowroot have cooked properly.
✤ Cool the crisp uncovered. Covering it while warm traps steam and softens the oat topping.
✤ For larger clusters, don’t overmix. After combining the topping, gently squeeze a few portions together with your fingers before scattering them over the fruit.
5. Cool before serving
- Let the crisp rest for about 10–15 minutes before serving.
- The plum juices will continue to thicken as the crisp cools.
- Serve warm, at room temperature or chilled, on its own or with vanilla ice cream, dairy-free ice cream or plain yogurt.
If blackberry season overlaps with your apples, my apple blackberry crisp with oat walnut topping is a good next one to try. The berries give it a deeper, more tart filling than this softer plum version.
Apple Plum Crisp FAQs
For an American audience, I call this an apple plum crisp because the topping contains rolled oats and bakes into a crunchy layer. In the UK and some other places, a similar dessert may be called an apple and plum crumble with oats. The names overlap, but crisp better describes this particular oat-based topping.
Most varieties work well, including black, red, purple and yellow plums. The most important thing is ripeness. Choose plums that have good flavor and give slightly when pressed but are still firm enough to slice.
No. Plum skins soften during baking and contribute color, flavor and a little structure to the filling. I prefer leaving them on.
Yes. Prepare the fruit filling and oat topping separately and refrigerate them for up to 2 days.
Assemble just before baking so the topping doesn’t absorb moisture from the fruit.
Yes. For the best topping texture, assemble the crisp and freeze it before baking for up to about 2–3 months.
Bake from frozen, allowing additional time until the filling is bubbling and the topping is golden.
If you still have ripe plums to use up, try my cherry plum dairy-free ice cream next, it’s a completely different way to enjoy them, with a cool, creamy texture and the same sweet-tart plum flavor.
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If you try this apple plum crisp recipe, leave a comment below and a star ★★★★★ rating if you enjoyed it. Your feedback not only helps other readers, but also helps me continue testing and creating recipes
Apple Plum Crisp with Oats & Walnuts
Ingredients
Apple And Plum Filling
- 2 large apples - I used Gala, thinly sliced
- 5-6 medium plums - sliced
- 4 tbsp maple sugar - or other granulated sugar
- 2 tbsp arrowroot flour
- 1 tsp cinnamon
- 1 tbsp lemon juice - optional (if the plums are too sweet)
Oat Walnut Topping
- 1 cup rolled oats
- ⅓ cup all purpose flour - for gluten free see notes
- ½ cup walnuts or pecans - crushed
- 6 tbsp butter - for dairy free / vegan see notes
- ⅓ cup maple sugar - or your favorite granulated sugar
- ¾ tsp cinnamon
- ½ tsp cardamom
Instructions
- Chill the butter. Freeze the butter for at least 1 hour before making the topping.
- Make the topping. Grate the frozen butter into the flour and toss to coat, or pulse the butter and flour briefly in a food processor until coarse crumbs form. Add the oats, walnuts, maple sugar, cinnamon and cardamom and mix just until combined. Refrigerate while preparing the fruit.
- Preheat the oven to 360°F (182°C).
- Prepare the fruit. Core and thinly slice the apples. Pit the plums and cut into slightly thicker wedges, leaving the skins on.
- Make the filling. Add the apples and plums to a 9-inch square baking dish. Toss with the maple sugar, arrowroot, cinnamon and optional lemon juice. Spread into an even layer.
- Assemble. Scatter the chilled oat-walnut topping loosely over the fruit.
- Bake. Bake for about 38–40 minutes, until the topping is golden and the filling bubbles around the edges. Loosely tent with foil if the topping browns too quickly.
- Rest. Cool uncovered for 10–15 minutes before serving.
Notes
Nutrition
The information shown is an estimate provided by an online nutrition calculator.
Looking for more warm-weather ideas? Browse my gluten-free and dairy-free summer desserts.
From juicy summer fruit to cozy nutty desserts, here are a few more whole-food treats to make next.
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I love how this recipe uses natural sweetener in moderate quantities without affecting your blood sugar. Thanks for inspiration!
You’re welcome! Enjoy more often then!
I had a ton of plums and now I know how to use them purposefully. They started to go bad and this is a perfect fruit dessert for using them. Loved it, thank you!
Thank you! I’m glad you tried it!