Rhubarb Crumble Bars are a must bake summer dessert recipe. They feature a thick and generous base, a juicy, sweet and tart rhubarb compote, and a crispy oat crumble on top.
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An original crumble bars recipe
I had high expectations about this dessert as it reminded me of something I used to eat when I lived in Sweden, although I couldn’t quite remember what it was exactly or name it. It was like a pie, but like a crumble on top, like bars, but on the pie side… In short, I was looking for an awesome rhubarb dessert, stuck in my memories, and I was determined to make it happen.
I created crumble bars. Berry crumb bars are very popular, and there are indeed countless of raspberry crumble bars recipes (the healthy ones that look almost too fragile, the ones made with the exact same crust for the top and bottom parts, and the other ones with an insane amount of sugar). Well today, I’m sharing rhubarb crumb bars instead, and I bet you will soon be obsessed with them!
A juicy, tart and sweet rhubarb dessert
While searching for the perfect rhubarb crumb bars recipe, I took some time to check the recipes in Swedish (yep, I can still read Swedish!). Interesting fact: I noticed that Swedish recipes contain most of the time half the amount of sugar American recipes contain.
When it comes to fruit desserts, it’s important to find the right amount of sugar to subtly enhance the flavors but in no way overtake the actual taste of fruits. With rhubarb, this is even more true! Slightly tart by nature, rhubarb calls for a little sugar to enhance its natural flavor, but not too much. This way, you get the perfect balance between tart and sweet.
Ingredients to make rhubarb crumble bars
- Rhubarb. You will need about 4 to 5 long stalks of rhubarb, or approx. 1.3 lb (550g).
- Lemon (zest + juice). It adds a bright flavor as well as a boost of natural pectin to help thicken the rhubarb compote.
- Sugar. It makes the compote a little sweeter and adds a subtly crunchy bite to both the bottom and top crust.
- Cornstarch. It is used to thicken the rhubarb compote.
- All-purpose flour. For both the bottom pie crust and the crumble topping.
- Baking powder. It makes the bottom crust a little thicker and softer, close to a blondie texture.
- Butter. While butter for the bottom part is used softened, the one for the crumble topping is used melted, bringing an irresistible crispy texture.
- Oats. Prefer old-fashioned rolled oats rather than quick oats, they hold their shape much better and do not become mushy.
How to make the rhubarb filling?
Making the rhubarb compote is easy. Stir all the compote ingredients except the cornstarch in a saucepan, and cook on medium heat until bubbling. Lower the heat and add cornstarch, stirring well. Let simmer for 5 more minutes, until the mixture thickens. Let cool for a few minutes before using.
What crust to use for these crumble bars?
Many recipes using the exact same crust at the bottom and top part of the bars. This would have been an easier version for you, I confess. But let’s get out of our comfort zone for a minute and make 2 crusts. The idea? Create a contrast between a rich, buttery bottom, and a crispy top. Both preparations are really easy to make, and you can totally re-use the same mixing bowl for each of them.
The bottom part. To create a rich, buttery and soft bottom crust, I used softened butter (instead of melted butter) and a little bit of baking powder.
The top part. To make it crumbly and perfectly crispy, I used oats and melted butter, with a little bit of sugar.
Baking tips and recipe variations
Bake in a square pan if you want to slice into squares like I did, or use a regular pie dish if you want to slice it in a more classic way. Both versions work equally well.
Note that you can follow the recipe to a T, or you can do half rhubarb and half strawberries. Rhubarb and strawberries go hand in hand together, like for instance in my Meringue Strawberry Rhubarb Pie. Another classic combo is rhubarb and apples. Or if you are interested in the bars but do not have rhubarb at hand, try with any berries of your choice: blueberries, blackberries, raspberries… Serve as is, or with a side of vanilla ice cream or whipped cream, and enjoy!
How to store crumble bars?
You can store these rhubarb crumble bars sliced into squares in an airtight container or in a ziploc bag for a week in the refrigerator and up to 3 months in the freezer. Thaw in the refrigerator for a few hours before eating. Enjoy!
What to do with rhubarb?
- Rhubarb Strawberry Chia Pudding
- Meringue Strawberry Rhubarb Pie
- Swedish Rhubarb Cardamom Buns
- Rhubarb Strawberry Apple Cobbler
- Geometric Rhubarb Galette
More fruit crumble recipes:
- Quick Pear and Chocolate Crumble
- Chai Spiced Dutch Apple Pie
- Best Apple Crumble
- Oat Crumble Blueberry Pie (GF)
Rhubarb Crumble Bars
- Prep Time: 30 mins
- Cook Time: 20 mins
- Total Time: 50 minutes
- Yield: 9 servings 1x
- Category: Cakes and Pies
Rhubarb Crumble Bars are a must bake summer dessert recipe. They feature a thick and generous base, a juicy, sweet and tart rhubarb compote, and a crispy oat crumble on top.
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Ingredients
For the base:
- ½ cup (100g) sugar
- 2 cups (240g) all-purpose flour
- 1 Tablespoon baking powder
- ⅔ cup (150g) salted butter, softened at room temperature
- 1 large egg
For the rhubarb compote:
- 4–5 long rhubarb stalks (3 ½ cups / 550g) diced rhubarb
- ⅓ cup (65g) sugar
- 1 lemon, zest and juice
- 2 ½ teaspoons cornstarch
For the crumble topping:
- 1 cup (100g) old-fashioned rolled-oats
- ½ cup (100g) sugar
- 1 teaspoon vanilla sugar
- ½ cup (100g) salted butter, melted
Instructions
- Preheat the oven to 400°F (200°C) and grease a 9-inch square pan. Set aside.
For the base:
- Mix all the dry ingredients together. Incorporate softened butter and pinch of salt with your finger tips until no lumps remain. Add the egg, and stir well until the dough comes together.
- Transfer the dough to the pan in a thick layer, covering all parts of the bottom of the pan.
For the rhubarb compote:
- Heat rhubarb with sugar, lemon zest and juice on medium heat until bubbling. Lower the heat and add cornstarch, stirring well. Let simmer for 5 more minutes, until the mixture thickens.
- Let cool for 5 minutes, then pour over the base in the pan.
For the crumble topping:
- Mix all the ingredients together and sprinkle over the rhubarb compote.
- Bake for about 20-25 minutes, until the top is slightly golden. Let cool completely, then share in square, and enjoy!
Did you make this recipe?
Lastly, if you make this Rhubarb Crumble Bars, be sure to leave a comment and give this recipe a rating, letting me know how you liked it. And of course, don’t forget to tag me on Instagram! Thank you and enjoy!
Kimberly Morash
I have made these bars 3 times now. the first two I followed the recipe to the letter and they were tasty, but the crumble was a greasy mess. the third time I added 1/4 cup of flour to the crumble. it was more to my liking. Regardless of this, the taste was amazing. Thank you for sharing your delicious recipe.
Delphine Fortin
Happy you liked it. Thanks for your feedback, Kimberly!
Jennj
These are fantastic! Hard to not keep sampling all day.
Delphine Fortin
So happy you liked them. Thanks for your feedback, Jenni! Del
Patti Seaney
Excellent! Made recipe as written except I used a 7×10 pan. ( I don’t have a 9 inch square) Still baked it for 25 minutes. This is a keeper for sure!
Delphine Fortin
Thank you for your feedback, it makes me so happy!
Jerry Paul
Easy to make. I’m 71years old and love all sweets. This rhubarb crumb bar is on my make again list. I’m making it again tonight to share with my neighbor. Thank you very much.
Delphine Fortin
I’m so happy you liked it. Thank you for your feedback, I truly appreciate!
Daria
Thank you for the recipe! These bars are delicious and I’m making again tomorrow. I didn’t have the vanilla sugar so I added some vanilla extract to the melted butter for the topping. I read other reviews for the topping and added 1/2 cup flour to the oats and the crumble came out beautifully. We love rhubarb and this is a really great recipe!! Thanks
Delphine Fortin
Thank you, Daria!
Psymama
This was divine! Family has pronounced it the best bars I’ve ever made. They’ll be gone soon. Thank you!
Delphine Fortin
Awesome, this makes me so happy! Thank you so much for your very nice feedback and awesome rating! Del
Steve
Does the cook time change when you triple the ingredients?
Delphine Fortin
Hi Steve! It all depends on the size of the baking pan you will be using when you triple the recipe. I recommend to check the baking time closely and adjust accordingly. I hope this helps. Del
Julie
My rhubarb I have been “growing” for 3 years finally took off this spring so I decided to try this recipe.
I taste as I go, and made some small modifications to get some flavor into it. I added a pinch of good salt into all three layers, vanilla and some cinnamon in the top crumble. I cut back on the butter by two tablespoons based on some of the comments, and still got kind of a greasy topping. I sprinkled on probably at least half a cup extra dry oats about half way through to soak some of it up and that helped but it isn’t as crispy as I had hoped. I had a lot of bottom crust left too, the bottom would have been 2 inches thick if I had used it up. The crust was a solid 3/4 inch thick and I filled a tart dish to the brim between the crust, filling and extra oats.
Overall it’s a good recipe, I liked it and will be making it again. It is still cooking so I can’t for sure say it came out all right, but all the elements tasted good!
Delphine Fortin
Thank you, Julie, for your feedback and sharing with us your personal adjustments to the recipe! Del
Deb
If I double the recipe what size pan should I use?
Delphine Fortin
Hi! If doubling the size of these bars, double the size of the pan mentioned in the recipe. I hope this helps!
Linda
Thea Swede a big hit! My husband says it’s the best rhubarb dessert he’s had, and my visiting daughter, who is a rhubarb connoisseur, had 3 bars! The perfect blend of sweet and tart
Delphine Fortin
Wow, that’s a success indeed! Thank you for your feedback, I’m really glad you all enjoyed these rhubarb bars!
Cindy
These bars sounded so yummy, but I must have done something wrong! My topping turned into a greasy melted butter slick instead of crumble! My pan was the right size, and I followed the recipe. Could it be that I used old fashioned oats and should have used quick?
Delphine Fortin
Hi Cindy! It seems to me that something went wrong during the baking time. Make sure you bake the bars in the middle rack position (not lower), and long enough to allow the topping to become crispy. On this note, the top crumble part is supposed to be crispy, not crunchy, unlike a classic crumble top (that usually requires more flour) and turns out more crunchy. I hope this helps! Del
Tan
Well loved in our house. It was very hard to stop eating it in one go! And we have a couple of very picky teenagers. We loved the perfect balance of sweet and tart. It likely will not survive day two
Delphine Fortin
So happy to learn than even picky teenagers liked the recipe. Thanks for letting me know! 🙂
Jean Williiams
This is the nicest, tastiest rhubarb dessert! The proportion of base/ compote / topping is perfect to create a beautiful looking and tasting bar. I enjoyed the layered variety of textures. I actually served them for brunch and they were a hit. I didn’t change any of the ingredients and used a combination of red and green rhubarb for a pretty pink color.
Delphine Fortin
Thank you, Jean, for your feedback! It truly makes me so happy that you liked it! Del
KerriLyn VH
Superb recipe, my new go-to for sure. Nice shortbread style crust and crispy oat topping. Doubled the quantity of rhubarb to about 6 cups, because it’s awesome. Added about 1 1/2 cups of blackberries. Still set up beautifully and had a nice ratio of fruit to thick bottom crust. Happy Spring.
Delphine Fortin
I’m so glad you liked it! Thank you so much for sharing your feedback about these rhubarb crumble bars. Happy Spring to you too!
Pam
The topping calls for vanilla sugar. What is that?
Delphine Fortin
Hi! Vanilla sugar is something we find in European stores mostly, but basically it is sugar mixed with vanilla beans. You can skip it and use regular sugar instead for still a fairly good result. I hope this helps! Del
Mary Alderton
Really nice recipe… I only put 50grms of sugar both in the base and topping and also reduced the butter in the topping to 50grm.
Perfection! Used lovely young rhubarb from the garden but will be making again with other fruit.
Delphine Fortin
So happy you liked the recipe. Thanks for your feedback, Mary! And yes, the recipe works with other fruits too. You can try with apples, blueberries, etc.