Our Rhubarb Crunch balances a bright, tart rhubarb filling with a buttery, crunchy oat crumble topping. Quick and easy to prepare, this dessert highlights fresh rhubarb in a comforting, old-fashioned dish.
When rhubarb season arrives, this simple rhubarb crunch is one of the first recipes we bake. Below is an easy-to-follow overview showing what you need and how to make it.
What is Rhubarb?
Rhubarb is a spring vegetable that looks and snaps like a pink celery stalk. Although often treated like a fruit in desserts, it is technically a vegetable and is very tart raw. Note: rhubarb leaves are poisonous and should never be eaten.
Sweetened and baked, rhubarb becomes an excellent base for crisps, crumbles, and sauces. Out of season, frozen rhubarb works well in most recipes.
What is Rhubarb Crunch?
Rhubarb Crunch is similar to a fruit crisp but features a hearty oat streusel that bakes to extra crunchiness. You may also see it called rhubarb crisp in some recipes.
Ingredients you’ll need for Rhubarb Crunch
- Fresh rhubarb — cleaned and diced.
- Granulated sugar — to balance the tartness.
- Cornstarch — for thickening the filling.
- Water — to make the cornstarch syrup.
- Vanilla extract — for flavor.
- All-purpose flour — swap for a 1:1 gluten-free flour if desired.
- Rolled oats — old-fashioned oats give the best texture.
- Brown sugar — light or dark both work.
- Ground cinnamon — optional, adds warmth.
- Butter — melted, for the crumble topping.
How To Make Rhubarb Crunch
This overview covers the main steps. The printable recipe card includes exact quantities, timing, and nutrition details.
Step One. Prepare
Preheat the oven and lightly grease a 9×13 baking dish. Clean and dice the rhubarb into evenly sized pieces (about 1/2 inch is recommended) and place them in the dish.
Step Two. Make the thickener
In a saucepan, whisk together water, sugar, and cornstarch until smooth. Heat over medium, stirring until the mixture thickens into a syrup. Stir in vanilla.
Step Three. Combine filling
Pour the thickened syrup evenly over the diced rhubarb in the baking dish, gently tossing if needed to coat the pieces.
Step Four. Make the topping
In a bowl, mix flour, oats, brown sugar, and cinnamon. Pour in melted butter and stir until the mixture is evenly moistened and crumbly. Spread the crumble over the rhubarb so the filling is covered.
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Crunch topping -
Add melted butter
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Crumble topping
Step Five. Bake
Bake uncovered at 350°F for 35 to 45 minutes, until the filling is bubbly at the edges and the topping is golden brown.
What to Serve with Rhubarb Crunch
Serve warm or cold. A scoop of vanilla ice cream or a dollop of whipped cream pairs beautifully, but it’s also delicious on its own. It works well for breakfast, a snack, or an easy dessert.
Frequently Asked Questions
Can I use frozen rhubarb instead of fresh?
Yes. Thaw frozen rhubarb before baking so excess moisture can drain. Place it in a colander over a bowl at room temperature or thaw overnight, then blot any extra liquid with a paper towel. Do not squeeze, which can make the filling too wet.
How do I know the rhubarb crisp is done baking?
The filling should be hot and bubbling around the edges and the topping should be golden and crisp.
Can Rhubarb Crunch be made ahead?
Yes. It stores well in the refrigerator and can be served warm or cold. Prepare a day ahead and reheat before serving if you like it warm.
How To Reheat & Store Rhubarb Crunch
Best way to store
Cover leftovers tightly with foil, plastic wrap, or a lid and refrigerate for 3–5 days to keep the topping from getting soggy.
Can I freeze it?
Yes. Freeze a whole pan or individual portions in airtight, freezer-safe containers. Thaw in the refrigerator before serving.
How to reheat
Microwave single servings for 15–30 seconds to warm. For a whole pan, reheat at 300°F until heated through and bubbling.
Tips for the Perfect Rhubarb Crunch
- No need to peel rhubarb—just remove the leaves and trim the bottom of the stalks.
- Chop rhubarb into uniform pieces (about 1/2 inch) so the filling cooks evenly.
- You can increase the amount of rhubarb without changing the topping; just be sure the baking dish bottom is covered.
- Old-fashioned rolled oats give the best crunch; quick oats will work but the texture will be different.
If you have an abundance of rhubarb, consider other favorites like rhubarb custard pie, rhubarb cake, or strawberry-rhubarb bread. Rhubarb sauce also makes great use of extra stalks.
I hope you enjoy this easy, delicious rhubarb crunch. Leave a comment and rating if you try it—your feedback helps other home cooks decide if this recipe is right for them.
Rhubarb Crunch Dessert
Pin Recipe
Equipment
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9×13 Baking Dish
Ingredients
- 4 cups rhubarb chopped 1/2″ thick
- ¾ cup sugar
- 2 tbsp cornstarch
- 1 cup water
- 2 tsp vanilla extract
- 1 cup all-purpose flour
- ¾ cup rolled oats old-fashioned
- 1 cup brown sugar
- 2 tsp ground cinnamon
- ½ cup butter melted
Instructions
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Preheat the oven to 350 °F and spray a 9×13 baking dish with non-stick spray.
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Place diced rhubarb in the bottom of the baking dish.
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In a medium saucepan combine water, sugar, and cornstarch. Whisk until smooth and heat over medium, stirring occasionally, until thickened. Stir in vanilla.
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Pour the cornstarch mixture evenly over the rhubarb.
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In a separate bowl, mix flour, oats, brown sugar, and cinnamon. Add melted butter and stir until crumbly. Sprinkle over the rhubarb.
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Bake uncovered for 35 to 45 minutes until bubbly and golden.
Notes
Store covered in the refrigerator.
Nutrition
Nutritional Disclaimer
Nutrition was calculated using the specific brands and amounts used for this recipe. If you follow a strict diet, changing ingredients or amounts will change the nutrition; use this as a guide.
If you enjoy fruit desserts with a crunchy topping, try other classics like apple crisp, peach crisp, or pear crisp for more seasonal options.
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