Blueberry rhubarb bars are the perfect dessert for spring and early summer! Made with rolled oats, their texture is reminiscent of rhubarb crumble but in bar form.

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Nothing signals the start of warm weather quite like rhubarb season. And as a veggie blogger, I like to give my fair share of attention to this tart stalk that’s technically a vegetable!
Since it’s usually paired with strawberries, rhubarb often gets mistaken for a fruit. But I was so thrilled to figure out that it was actually a veggie and that I could therefore add it to more blog recipes, especially since I like to offer both sweet and savory dishes on the site.
So, welcome to my annual ode to rhubarb! This year’s creation is a delicious twist on rhubarb crumble. I created these Blueberry Rhubarb Bars using my Blueberry Rhubarb Jam (that I posted last year) and an amazing gluten free, oat-based crust.
The result? REALLY good!! The bars are sweet, tart, and just the right amount of crumbly. Make sure you capitalize on rhubarb season while you can and make this dessert before it’s over! You won’t be disappointed.

How to Make Blueberry Rhubarb Bars
The process for this recipe is really easy. Honestly, the most difficult part is blending half of the oats to make oat flour. If you make the jam in advance (see this post for details), you can whip these up in less than an hour.
Here are the steps:
- Combine the oat flour, oats, and slices of butter in a mixing bowl.
- Use a pastry cutter or your hands to mix the batter into a crumble.
- Press half of the batter into a greased 8×8 baking dish. Bake for 12 to 15 minutes until lightly brown.
- Pour the jam on top of the crust.
- Spread it out into a single layer.
- Press the rest of the batter on top of the bars. Pop back in the oven!
Expert Tips
- You can make the jam up to a week before making my Blueberry Rhubarb Bars. Store it in the fridge in an airtight container until you make the recipe. You can also freeze the jam and make these at a much later time. Let it thaw in the fridge before using.
- Let the bars cool completely before slicing. The jam will thicken up a little more while they cool, making them easier to slice. Please note that the bars are intended to be crumbly, like a rhubarb crumble.
- Store the bars in an airtight container at room temp for up to a week. I haven’t tried freezing them, but I imagine it would work.
- You can sub other jams for the filling, like a strawberry rhubarb jam instead, if desired.
- If you need these bars to be gluten free, use certified gluten free rolled oats.

If you like these bars, you may also enjoy the Sweet Strawberry Rhubarb Salsa and the Strawberry Rhubarb Baked Oatmeal Muffins. For other recipes with blueberries, check out the Blueberry Sweet Corn Frozen Yogurt Bark and Sweet Potato Blueberry Flax Muffins.

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📖 Recipe

Blueberry Rhubarb Bars
Ingredients
- 3 cups rolled oats - divided; use certified gluten free if needed
- ½ cup unsalted butter - cut into slices
- ½ cup packed brown sugar
- ½ teaspoon baking soda
- ¼ teaspoon salt
- 1 cup Blueberry Rhubarb Jam - see notes for recipe link
Instructions
- If you have not prepared the jam, follow the instructions in this post. Once the jam is ready, follow the next steps.
- Preheat the oven to 350 degrees F. Grease an 8×8 baking dish and set aside. Add 1.5 cups of the oats to a blender and blend until you have a fine oat flour. Transfer the oat flour to a mixing bowl and add the rest of the whole oats, sugar, baking soda, and salt. Add the butter, and using a pastry cutter or just your hands, mix the butter and oat mixture together until it's crumbly.
- Press half of the mixture into the greased baking dish, and bake for 12 to 15 minutes until fragrant and lightly brown. Remove from oven and pour the jam on top. Use a spatula to spread it into an even layer. Press the rest of the oat mixture on top of the jam, and bake for 25 to 30 minutes until lightly brown.
- Remove from the oven and let it cool completely before slicing into 9 bars. The jam will thicken up as it cools, making the bars stay together better.
Notes
- Plan for longer prep time if you haven’t made the jam in advance. You can keep the jam in the fridge for up to a week, or you can freeze the jam and make these bars at a much later time if desired.
- Store the bars in an airtight container at room temp for up to a week.
- Please note that the bars are intended to be slightly crumbly, like a rhubarb crumble.
Nutrition
Enjoy rhubarb season! – Lizzie
Judy Wildgrube
Wonderful receipe as was the blueberry jam made jam in micro dessert in my oven airfryer
Lizzie Streit, MS, RDN
Hi Judy, I’m so glad you enjoyed the bars and the jam! Thanks for your review!