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Old-fashioned Rhubarb Crunch begins with a brown sugar oatmeal crumble layer that is topped with fresh rhubarb and then it is finished with a second layer of crumble over the top.
The Strawberry Rhubarb Fruit Crisp is an ever-popular dessert in the summertime and this crunch variation takes it to an even tastier new level.
I hope you’re enjoying as beautiful of a spring as we are! I’m so happy to be deep into rhubarb season and I’m looking forward to more fruit desserts through the summer as well.
I’m excited to be working on more rhubarb recipes again this year. We have so many to share and I’m working through a list of them for you!
So far, I’ve shared a Rhubarb Crisp, Rhubarb Cake with Butter Sauce, Rhubarb Bars, Old Fashioned Rhubarb Pie and the Double Crumb Rhubarb Coffee Cake.
This No Churn Rhubarb Ice Cream from Our Table for Seven and this Strawberry Rhubarb Galette from 365 Days of Baking are also on my list to try soon.
What is a Rhubarb Crunch?
A fruit crunch is similar to fruit crisps, but it has an oatmeal crumble layer on the bottom as well as a top.
Similar to a bar, but still gooey enough to eat with a spoon. It’s perfect with a scoop of vanilla ice cream or a dollop of freshly whipped cream.
A generous amount of brown sugar in the crumb layers and plenty of white sugar for the filling nicely balances the tartness of the rhubarb.
How to Make Rhubarb Crunch?
First you’ll start by making a brown sugar oatmeal crumb layer. Melt some butter and add oatmeal, flour and brown sugar. Mix until crumbly.
Press half of these crumbs on the bottom of the pan. Then top with some chopped rhubarb. You can use fresh or frozen.
If you choose to use frozen rhubarb, you’ll want to check out the section below on how to use frozen rhubarb in this rhubarb crunch recipe.
The next step of the recipe is what makes the rhubarb crunch unique. You boil a mixture of water, sugar and cornstarch until thickened and bubbly.
Then pour the mixture over the rhubarb in the pan. Top with the remaining half of the oatmeal crumb mixture and bake for about an hour.
Like most fruit crisps, I think a crunch is best served warm with ice cream or whipped cream, but the leftovers are also delicious the next day, eaten cold straight from the refrigerator.
How to use frozen rhubarb in this recipe?
You can make this recipe using fresh or frozen rhubarb.
If you choose to use frozen rhubarb thaw the rhubarb first and let any excess liquid drain off. Don’t squeeze any liquid out, just drain what naturally thaws out of the rhubarb.
You’ll want to plan ahead to use frozen rhubarb. Depending on the temperature of the room, it takes 4-6 hours to thaw a quart of rhubarb completely.
So you may want to take it out of the freezer the night before. When in a pinch, I’ve also used the auto defrost feature on the microwave to give it a head start, just be careful not to heat it too high and cook it.
Rhubarb Crunch Recipe
- Preheat oven to 350° F. In a medium bowl, combine the flour, oatmeal, brown sugar, melted butter and cinnamon until crumbly. Press 1/2 of the crumb mixture into a greased 9 x 9 inch or 11 x 7 inch baking pan.
- Spread the diced rhubarb in the pan. In a small saucepan, combine the white sugar, water and cornstarch. Bring to a boil over low heat. Continue to cook and stir until the mixture is thick and clear. Pour the sugar mixture over the rhubarb in the baking pan. Top with the remaining crumb mixture.
- Bake for 1 hour. Cool at least slightly before serving. To serve, cut into squares and top with ice cream or whipped cream. Best served warm.
Looking for more rhubarb recipes? Full of tender apples, beautifully citrusy rhubarb, and crowned with a classic brown sugar oat crisp topping, Apple Rhubarb Crisp blends seasons together in sweet tart harmony. It’s different and it’s delightful!
Rhubarb Crunch
Ingredients
- 1 cup all purpose flour
- 3/4 cup quick cooking oatmeal
- 1 cup brown sugar
- 1/2 cup melted butter
- 1 teaspoon cinnamon
- 4 cups diced rhubarb
- 1 cup white sugar
- 1 cup water
- 2 tablespoons cornstarch
- Vanilla ice cream or whipped cream for serving
Instructions
- Preheat oven to 350° F. In a medium bowl, combine the flour, oatmeal, brown sugar, melted butter and cinnamon until crumbly. Press 1/2 of the crumb mixture into a greased 9 x 9 inch or 11 x 7 inch baking pan.
- Spread the diced rhubarb in the pan. In a small saucepan, combine the white sugar, water and cornstarch. Bring to a boil over low heat. Continue to cook and stir until the mixture is thick and clear. Pour over the rhubarb in the baking pan. Top with the remaining 1/2 of the crumb mixture.
- Bake for 1 hour. Cool at least slightly before serving. To serve, cut into squares and top with ice cream or whipped cream. Best served warm.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
{originally published 4/11/19 – recipe notes and photos updated 5/25/21}
Made it according to recipe – no changes. Absolutely delicious!
I’m thrilled that you enjoyed it, Emme!
I’m about to bake this. In the bottom version of the ingredients, water is included, but that line is missing from the ingredients at the top of the page and on the photo.
Yes, you do need the water. It isn’t always listed with ingredients you’ll need to gather or have on hand, but it is in the recipe card and instructions. Happy baking!
Could I use old fashioned oats instead of quick oats?
That should work fine, Taylor. The crunch will have a slightly more defined texture this way. I use both kinds of oats when I make this.
This rhubarb crunch is absolutely delicious! My nephew, who is 10 years old, requested the recipe so that he could make it for when they had company coming over 🙂 It’s a definite keeper!!
Love this recipe. So easy to make and just delicious
Yummmm, I am making this today!!!
This is absolutely delicious. My husband couldn’t stop complimenting me on the recipe. Made just like recipe but only had 3 cups of rhubarb. Still wonderful.
Part 2 was like rock candy by the time it got clear and thick …. ahhhh
Never got clear. When it was really getting goopy I decided to take it off. It’s baking now. Was looking through comments to see if anyone else had it not turn perfectly clear.
Hopefully, it baked up delicious for you Sabrina.
Cornstarch is fussy. The 2 Tbsp sounds a bit much for 1C of water but then have to take into consideration that the rhubarb the rhubarb will make some juice too.
Also, you have to be sure cornstarch is well mixed into the COLD water. Can’t add it to hot water EVER. May be the reason it wasn’t the consistency needed.
I would mix the cornstarch into the COLD cup of water before adding it to the sugar ( which I’d cut down to 2/3 C) in the pan before turning heat on under it. Bring to boil stirring often; turn down to simmer and stir for couple minutes. Take it off the heat.
I mixed mine with the cold water and it’s still not thickening? Been boiling for a good 10-15 min.
It shouldn’t take that long, Kari. Did you mix the rhubarb with the water? I’m a little unclear here. You should’ve been able to bring the water + sugar + cornstarch to a boil and then it will thicken pretty quickly. That syrup is then poured over the rhubarb in the pan.
This is such a FANTASTIC recipe!!! Love it!!
Thank you for sharing!!!
Okay, followed the recipe, had doubts at stage 2, looked like the picture but completely inedible. If I try again will be without cornflour and half the sugar. Seriously, 3 cups?
Cornflour? It’s cornstarch. Made it and it was very good.