Rhubarb Oat Crumble Bars

Rhubarb Oat Crumble Bars

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Looking for a quick, easy seasonal dessert? Rhubarb Oat Crumble Bars are perfect for any spring occasion from Memorial Day cookouts to a relaxing summer night on the back porch. When I first tried this recipe, I had no idea how it would turn out, but it ended up being a major success! For the oat crumble, I used the same recipe as my Refined Sugar Free Date Bars, except this time I made a sweet rhubarb jam filling. The results were nothing short of fabulous.

Notes on the Filling

I’ve now made two batches of these bars. The first attempt I made as it is written in the recipe below, but the second time, I doubled the rhubarb filling. Both ways work just fine, though you’ll need to bake for a bit longer with extra filling. If your favorite part is the buttery oat crumble, then stick with the recipe as is, but if you love the fruity filling, go ahead and add more for a thick gooey bar. Also, now that strawberries are starting to blossom and will be ready soon, you you certainly try adding some to the jam as well. I know I’ll be trying that in a few weeks!

rhubarb oat crumble bars

Healthier Options

As usual, I’m always trying to make foods as healthy as possible. I wouldn’t classify Rhubarb Oat Crumble Bars as healthy, but they do have a few positive attributes. The first is using local, organic rhubarb. If you can’t grow your own, definitely check out your local farmers market because the freshest ingredients make for the best desserts.

I also eliminated refined sugar. I used raw, local honey in the filling and sucanat in the crumble. Sugar is still sugar no matter what and should be eaten in moderation, but at least these kinds are a little less processed. The flours are also unrefined. I used a blend of whole wheat pastry flour and ground oats for more fiber and a lower glycemic index than using refined white flour. Plus the oats add a nice, hearty texture.

Finally, there’s the butter. A lot of butter. But butter coming from pasture-raised cows is a much healthier alternative to shortening or industrial seed oils! I prefer using Irish butter or organic butter from Organic Valley because I can be sure there aren’t antibiotic residues in it and the cows are well cared for and enjoy lots of time in the sunshine on pasture. Grass-fed cows also produce more nutrient dense dairy products!

rhubarb oat crumble bars

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Rhubarb Oat Crumble Bars

Rhubarb Oat Crumble Bars are a new family favourite! The buttery oat crumble perfectly complements the sweet, yet tart fresh rhubarb filling.
Prep Time20 minutes
Cook Time50 minutes
Total Time1 hour 10 minutes
Servings: 12 bars
Rachel Alexandra


  • Food processor
  • 8×8 baking dish


Rhubarb Filling

  • 2 cups sliced rhubarb about 1/2 lb
  • ¼ cup water
  • 1 tsp tapioca starch or arrowroot
  • ¼ cup raw honey

Oat Crumble

  • cups old fashioned oats
  • ¾ cup whole wheat pastry flour
  • ¼ cup +2 Tbsp sucanat
  • ¼ tsp + ⅛ tsp baking soda
  • ¼ tsp Celtic sea salt
  • ½ tsp cinnamon
  • ¾ cup Irish butter cold



  • In a small bowl, whisk the water and tapioca starch.
  • Place the rhubarb in a small saucepan and add the water/starch mixture and honey. Stir to combine.
  • Bring to a boil over medium-high heat.
  • Reduce heat to medium-low and simmer for about 20 minutes or until the rhubarb is soft and the sauce has thickened.
  • Set aside to cool.

Oat Crumble

  • Line an 8×8 baking dish with parchment paper and preheat oven to 350°F.
  • Place the oats in a food processor and pulse until it forms a coarse flour.
  • Add the flour, baking soda, salt, cinnamon, and sucanat to the food processor and pulse a few times until combined.
  • Cut the butter into slices, add them to the food processor, and blend them into the dry ingredients. You may need to use a spatula to scrape down the sides and make sure everything is getting incorporated.
  • When the butter is mostly worked in, transfer the oat crumble to a bowl and knead the dough a few times by hand to make sure it is all evenly mixed.
  • Take ⅔ of the mixture and press it into the bottom of the prepared baking dish until it evenly covers the bottom.
  • Spread the rhubarb filling over the oat crumble in the dish.
  • Take the remaining oat crumble an sprinkle it on top of the filling as evenly as possible.
  • Bake for 20-30 minutes, until the top crust becomes golden brown and the rhubarb is bubbling.
  • Allow the bars to cool completely before slicing. Store leftovers in the refrigerator, but bring to room temperature before serving. Enjoy!


The rhubarb filling could be made ahead of time and stored in the refrigerator until ready to use.
Tried this recipe?Mention @roots_and_rosemary or tag #rootsandrosemary

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