Easy Rhubarb Crumble
A warm rhubarb crumble has a soft, jammy fruit filling under a crisp oat crumble topping. This easy rhubarb crumble keeps the tart flavor of fresh rhubarb balanced with brown sugar and butter.
Prep
15 min
Cook
45 min
Total
1 hr
Servings
6 servings
Ingredients
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Instructions
- 1
Preheat the oven to 375°F and lightly grease an 8×8-inch baking dish. Toss the chopped rhubarb with granulated sugar, cornstarch, vanilla, and lemon juice until the fruit looks glossy and evenly coated.
- 2
Spread the rhubarb mixture into the baking dish in an even layer. The filling may look dry at first, but the rhubarb releases plenty of juice as it bakes.
- 3
In a separate bowl, combine the oats, flour, brown sugar, cinnamon, and salt. Add the cold butter cubes and work them into the mixture with your fingertips or a pastry cutter until large crumbs form. The texture should look sandy with some pea-sized butter pieces still visible.
- 4
Sprinkle the oat crumble topping evenly over the fruit. Avoid pressing it down too firmly so the topping stays crisp instead of dense.
- 5
Bake for 40 to 45 minutes, until the fruit is bubbling around the edges and the topping is deep golden brown. If the crumble starts browning too quickly, loosely tent the dish with foil for the last 10 minutes.
- 6
Let the rhubarb crumble cool for at least 15 minutes before serving. The filling thickens as it rests, making it easier to scoop.
Used in this recipe: Glass Mixing Bowls (Amazon, affiliate links)
Nutrition (per serving)
490 kcal
Calories
5g
Protein
88g
Carbs
16g
Fat
3g
Fiber
200mg
Sodium
This rhubarb crumble puts tart, jammy rhubarb under a crisp oat crumble made with flour, brown sugar, cinnamon and cold butter. The fruit is thickened with a little cornstarch so it stays spoonable rather than watery, and the topping bakes up golden with clusters of oats. It fits an 8×8-inch dish and serves 6, with about 15 minutes of prep.
Ingredients
For the rhubarb filling
- 5 cups chopped rhubarb
- 3/4 cup granulated sugar
- 2 tablespoons cornstarch
- 1 teaspoon vanilla extract
- 1 tablespoon lemon juice
For the oat crumble topping
- 1 cup old-fashioned oats
- 1 cup all-purpose flour
- 3/4 cup light brown sugar
- 1/2 teaspoon cinnamon
- 1/4 teaspoon salt
- 1/2 cup cold unsalted butter, cubed
Old-fashioned rolled oats give the best texture. Quick oats go soft and steel-cut oats stay hard.
Timing: About 1 Hour Start to Finish
Prep is about 15 minutes and baking takes 40 to 45 minutes. That comes to about 1 hour, followed by a 15-minute rest before you scoop it.
How to Make Rhubarb Crumble
- Dress the rhubarb. Preheat the oven to 375°F and lightly grease an 8×8-inch baking dish. Toss the rhubarb with the granulated sugar, cornstarch, vanilla and lemon juice until glossy and evenly coated.
- Fill the dish. Spread the rhubarb in an even layer. It may look dry at first, but it releases plenty of juice as it bakes.
- Make the crumble. In a separate bowl, combine the oats, flour, brown sugar, cinnamon and salt. Work in the cold butter cubes with your fingertips or a pastry cutter until large crumbs form. It should look sandy, with some pea-sized butter pieces still visible.
- Top. Sprinkle the crumble evenly over the fruit without pressing it down, so it stays crisp instead of dense.
- Bake. Bake for 40 to 45 minutes, until the fruit bubbles around the edges and the topping is deep golden brown. If it browns too quickly, tent the dish loosely with foil for the last 10 minutes.
- Rest. Cool for at least 15 minutes. The filling thickens as it sits, which makes it easier to scoop.
Keeping the Filling Thick and the Topping Crisp
- Cornstarch is the thickener. It absorbs rhubarb’s extra juice so the dessert is spoonable, not soupy.
- Cold butter matters. Warm butter melts too fast, and the topping spreads and turns greasy instead of crisp.
- Do not pack the topping. Sprinkle it loosely so heat and steam can escape.
- Wait before serving. A watery crumble usually needs more cooling time or more thickener. The juices continue to thicken as it rests.
- Green, very tart rhubarb: Add an extra tablespoon or two of sugar.
Strawberry, Frozen Rhubarb and Other Variations
- Strawberry rhubarb: Replace 2 cups of the rhubarb with sliced strawberries. The fruit becomes sweeter and softer.
- Frozen rhubarb: Thaw it and drain the liquid before mixing. Frozen rhubarb releases more moisture, so add an extra teaspoon of cornstarch.
- Nuts: A small handful of chopped pecans or walnuts in the topping adds crunch.
- Bars and coffee cake: The same oat crumble works as a topping on bars and coffee cakes.
If you like rhubarb desserts, see our strawberry rhubarb crisp, strawberry rhubarb pie and rhubarb dump cake.
What to Serve With Rhubarb Crumble
Serve it warm with vanilla ice cream or lightly whipped cream against the tart fruit. For a richer dessert, spoon it over pound cake or serve it with custard in place of ice cream. It works as a simple summer dessert after a grilled meal or a hearty comfort dinner.
Make Ahead, Storage and Freezing
You can assemble the whole crumble several hours ahead and refrigerate it before baking, although the topping is crispest when baked fresh. Cover and refrigerate leftovers within 2 hours and eat within 3 to 4 days, reheating in the oven. To freeze, bake fully, cool completely, wrap tightly and freeze up to 3 months. Reheat uncovered in a 350°F oven until the filling bubbles and the topping crisps again.
FAQ
Can I use frozen rhubarb?
Yes. Thaw and drain it first, and add an extra teaspoon of cornstarch to keep the filling thick.
Why is my rhubarb crumble watery?
The filling needed more thickener or more cooling time. Let it rest at least 15 minutes before serving.
Can I make it ahead?
Yes, assemble it several hours ahead and refrigerate it before baking. Leftovers reheat well in the oven.
