Rhubarb Oatmeal Bars
Rhubarb Oatmeal Bars are everything you want from a spring or summer dessert: a buttery, crumbly oat base, a jammy rhubarb filling and a crumb topping that turns golden in the oven. They’re sturdy enough to pack for a picnic, sweet enough for dessert, and perfect for packing in lunch boxes.
This is a classic rhubarb bar recipe built on an oat and brown sugar crust that does double duty as the base and the crumbly topping. The filling is cooked on the stovetop first, which thickens the rhubarb into a jammy consistency before it ever goes in the oven. That extra step means the filling holds together in clean slices instead of turning watery, and the topping bakes up crisp instead of soggy.
Rhubarb has a short summery season, so this is the kind of recipe worth having ready to go when it shows up at the farmers market or in your garden. But luckily this recipe can be made with fresh or frozen rhubarb so freeze some now to make rhubarb bars all winter long. Want to know more about freezing and saving your rhubarb, read this post How to Freeze Rhubarb and other Rhubarb Secrets! When I’m looking to fill my freezer for the winter I always turn to my rhubarb patch!
Ingredients for Rhubarb Oatmeal Bars
These easy bars are based on pantry staples like rolled oats, flour, butter and brown sugar. Ingredients most of us have on hand. And you can use frozen rhubarb for these bars which means you need to get out to the garden NOW and get some rhubarb into the freezer to make these bars all winter long.
- rolled oats, you can use regular or quick cook for this recipe
- butter
- all-purpose flour
- baking soda
- brown sugar
- rhubarb, use fresh or frozen rhubarb
- white sugar
- water
Tools you’ll need:
- food processor
- saucepan
- 9×13 baking pan
We Love Rhubarb!
You guys KNOW I love rhubarb. I have a hard time not filling my freezer cram packed full of rhubarb for the winter. I do love to make summery desserts in the depths of winter to remind us that summer is coming, sooner or later.
We love a good Rhubarb Crisp, and of course Rhubarb Pie. Or make it with berries like in this fabulous this lattice topped Strawberry Rhubarb Pie or my Strawberry Rhubarb Pie but sometimes you just want cookie bars!
Got Leftovers?
To store these bars keep them lightly cover at room temperature for 2-3 days. If you cover them tightly the bars will get soft and crumbly.
Rhubarb Oatmeal Bars
Equipment
- Food Processor not necessary but nice to have
Ingredients
- 2 cups flour
- 1 1/3 cups brown sugar
- 1/2 tsp baking soda
- pinch salt
- 1 cup butter, salted if using unsalted use 1/2 tsp more salt
- 2 cups oatmeal quick cook or regular
Rhubarb Filling
- 4 cups rhubarb chopped
- 1/4 cup water
- 1 Cup sugar more or less depends on your taste
- 4 TBSP Flour
Instructions
- Preheat the oven to 350˚
- mix the the flour, brown sugar, and baking soda together in a food processor
- cut the butter in chunks and drop it in the dry mix, pulse to combine
- keep mixing until it looks like coarse crumbs
- Remove the blade from the food processor and add the oats
- using your hands work them into the crumb mixture
- save off 1 cup of crumbs
- press the rest in the bottom of a 9X13 baking dish, set aside
- put the rhubarb, water, and sugar in a sauce pan
- bring it to a boil over medium high heat, it will get very juicy as it cooks
- once it comes to a boil reduce the heat to keep it from scorching, just keep it bubbling lightly until the rhubarb is just starting to get soft
- remove 2/3 cup of the juice and whisk in the flour into it
- add it back in the pan and stir until thickened, cook and stir for 1-2 minutes and remove from the heat (congratulations, you just made rhubarb gravy!)
- spread the rhubarb over the base layer in the 9X13 sprinkle with reserved crumbs
- bake for 40-45 minutes until top is lightly brown and the rhubarb is bubbly
- let it cool before you cut it for best results
Video
Nutrition
- Strawberry Rhubarb Pie
- Slow Cooker Chocolate Cherry Cobbler
- Dubai Chocolate Brownies
- Biscoff Cups
- Strawberry Rhubarb Trifle
- Key Lime Pie Bars
- Chocolate Caramel Bars
- Heath Bar Poke Cake
What temperature do you bake these at?
350! Must have been taken out in the recipe conversion : ) Good catch!
I’m a BIG FAN of rhubarb! These bars look terrific! Pinning to my rhubarb board to try for sure.
A rhubarb board is #lifegoals
I love rhubard so much! These would be fantastic! And maybe I’ll add some strawberries. Fabulous recipe! P~
I love rhubarb! I thought these bars were delicious, next time I would cut back on the sugar, as they were too sweet for us.
Yes I always feel like there’s a fine line between just right and too sweet. But it’s also so personal too. Glad you enjoyed them.
I used my coworkers as a test for this recipe. They it. What little was left went to family and they agreed. This is a keeper. Thanks for sharing.
Oh Patty! I am so happy they liked my Rhubarb bars!
Can these bars be frozen
I have never frozen them–I don’t see why you couldn’t though? They might get soft though.
Maybe try one, see how it does.
I’ve made these, frozen them and wrapped them in baking paper to eat on a bike ride. They’re great for 2-3 hours, and a little soft after 4 hours in a handlebar bag. They’re almost perfect for /30 minute snacks at ~30 grams carbohydrate/serve.
I froze. A small batch in a cookie tin. Took one out, put it on a paper towel to thaw it a half hour later it wasn’t soggy. It was great. I’ll definitely freeze more.
Why couldn’t you use canned rhubarb if fresh isn’t available.
I’ve never seen canned rhubarb. Do you mean jam? I think you could try subbing that in. Let me know what happens!
I don’t see butter listed in the recipe but it is in the instructions?
OMGOSH good catch, I just switched recipe cards for this and it ate some of the ingredients. I’ve
added it back to the card but just so you know it was one cup of butter. Thanks so much for letting me know
about the mistake on these rhubarb bars!
I prefer large flake oats over the quick oats. Could you sub in this recipe?
Absolutely!
There is just two of us. What would we do to make 8″ x 8″ pan (glass)? They look good!
Could you use almond or coconut flour instead of white flour?
I have not tried that with this recipe. You can do some experimentation and find out though!
We have a lot of food allergies, and I used an all purpose gluten free flour and it works beautifully. I have made it both ways and we couldn’t tell the difference!
How much flour do you add into the rhubarb when it’s cooking?
The 4 TBSP listed down below the rhubarb.
If using frozen rhubarb, should it be thawed first or left frozen? Would I reduce the water for cooking?
I leave it frozen and reduce the water to just a splash!
Trying these today for the first time! In the oven, should it be on the center rack? Mine didn’t brown on the top and the rhubarb didn’t bubble although the bottom is nicely browned! Wondering if I should have moved it closer to the heat source? (My taste test fresh out of the oven was great! )
I do generally bake them on the middle rack.
This is one of our very favorite recipes! It’s always delicious and a huge hit with others.
Just making some now,hope they turn out!Have been canning so I’m tired,got hubby to help with the making of the crumbs.
Really good flavor! Bottom crust REALLY hard! Did I Pat it down to hard? Baked it to long? Baked it to hot? (350 for 35 minutes in glass 9×13).
These were really good. The crumble topping and crust were perfect. My only issue is it didn’t have enough rhubarb filling. Next time I’m going to use more rhubarb.
I followed the recipe to a T but I ended up increasing the oven temp to 425° to get it to bake completely without it coming out jiggly. (The oven is old but works fine.) ???