The blueberry squares at Starbucks are the inspiration for these Rhubarb Blueberry Oatmeal Bars. I had one of those a while ago, and it was delicious. And I knew I had to make a homemade version. Blueberries are in season now, and we had a bunch of sweet, juicy berries. And we also had rhubarb left from making Strawberry Rhubarb Muffins , so I decided to add that, too. Injecting a little bit of tartness was a good idea because blueberries and rhubarb were perfect together in these squares.
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It's Okay to Have a Treat Sometimes
Can we call these rhubarb blueberry oatmeal bars semi-healthy? Yes, there's butter and sugar. But they are made with fruit, and there are oats in there, too. But who am I fooling? These are a treat, no doubt about it. A delicious treat of blueberry rhubarb goodness between buttery oatmeal crispness. And we all need a treat sometimes. Life is about balance, and treats are part of that.
Blueberries are Great in Many Recipes
The best way to eat these fresh juicy blueberries, is of course, just straight up. At least for me. I can just plow through a bowl of these like they were peanuts. But I also like to showcase these luscious local berries in a recipe now and then, too. Like this Finnish Blueberry Pie, or Blueberry French Toast Casserole, or even in a savory dish like Blueberry Sourdough Sausage Stuffing, for your next holiday feast. You can even use these beauties in a cocktail. Try a Blueberry Ginger Martini, you won't regret it.
Can You Freeze These Bars?
The answer is yes. These bars freeze very well. To freeze, allow them to cool completely, then flash freeze them on a tray until just firm. You can then pack the bars in an airtight container or bag. Or you can wrap them individually for a grab & go treat that will be defrosted by lunch or coffee time.
Fun Facts About Blueberries
Did you know:
Blueberries freeze in only 4 minutes.
There are two types of blueberries; highbush, and lowbush. Highbush are the ones we buy in grocery stores and farmer's markets. Lowbush blueberries are smaller and sweeter and are used in jams, pie fillings, preserves, etc. Get more blueberry facts here: 10 Fun Facts About Blueberries
Recipe
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Rhubarb Blueberry Oatmeal Bars
Ingredients
- 3 cups fresh blueberries
- 3 cups rhubarb cut into 1-inch pieces
- juice of one lemon
- 1 cup sugar
- 4 tablespoon cornstarch
- 2.5 cups quick-cooking oats
- 1 cup all-purpose flour
- 1 cup brown sugar packed
- ½ teaspoon baking soda
- ¼ teaspoon salt
- 1 cup cold butter cut into cubes
Instructions
- Put blueberries and rhubarb chunks and lemon juice into a large, stainless steel pot, over medium heat
- Cook, stirring occasionally until rhubarb is softened.
- In a small bowl, whisk sugar and cornstarch together
- Add to fruit mixture, stirring constantly until thickened and smooth.
- Remove from heat.
- Heat oven to 350°. Prepare a 9 x 13 baking pan by spraying with cooking oil, or, lining with parchment paper.
- In a bowl, combine oats, flour, brown sugar, baking soda and salt.
- Using a pastry blender to cut butter into flour mixture until it resembles course crumbs
- Press half the flour mixture into prepared pan to form crust
- Spread blueberry rhubarb mixture over the bottom crust
- Spread remaining flour mixture over the fruit layer, pressing lightly
- Bake in center of oven until golden, about 45 minutes
- Cool completely on a wire rack before slicing into 24 squares
Notes
Nutrition
Susan
This turned out exactly as I'd hoped, lovely oatmeal crust, jammy filling and oat crumbles on top. My son-in-law said, "This is money!" We grow blueberries and a neighbor shared rhubarb. I had no problem with the fruit cooking down, no scorching and plenty of liquid. My only deviations are 1/2 tsp cinnamon added to the fruit and rolled oats for quick oats because that's what we buy. I'm making it again for tomorrow's potluck. Super yummy!
Colleen
I love hearing this, Susan! So lucky you are to grow blueberries. I'm happy that this recipe will be a part of your potluck tomorrow. Why I love what I do. Thank you for sharing!
Susan
This deserves a 1 star for sure. Lemon juice is listed in the ingredients, where is it in the recipe instructions? The directions say to put rhubarba and blueberries in the pot to cook. There is no liquid or sugar added at this time, so how do the rhubarb and blueberries cook down?? They don't, they burn. Luckily I know how to bake and made several modifications to the recipe so I could serve it to the guests at the picnic. I had already spent enough money on butter, fresh from the farm strawberries and rhubarb, so I was going to make it work one way or the other. I unpinned this right away after realizing that the directions are faulty.
Colleen
Hi Susan,
Thank you for letting me know about the error in my recipe. I have now corrected it to include adding the lemon juice with the blueberries and rhubarb. I tried to reply privately but you have used a fake email address.
Although websites like mine are a wonderful source of free recipes, keep in mind that they are created by humans who work very hard to develop and make them available to you.
Being human, I make the occasional mistake, of course, and I rely on my readers and taste testers to (kindly) point them out so that I can fix them.
I would however, like to point out that this recipe is made with blueberries, and not strawberries. I haven't tried it with strawberries, but I would think that your "fresh from the farm" strawberries do not contain as much water as blueberries. Even without the lemon juice, the fruit should not have burned, unless the heat was too high.
A one star rating is extremely wrong and very unfair. These bars are absolutely delicious and are a family favorite for us and for many other readers, who either missed the lemon juice omission, or just figured it out.
Although you didn't mention what the "several modifications" are that you made, I can assure you that none are needed other than my one small omission.
I am sincerely sorry that my omission of lemon juice in the recipe caused you so much trouble and made you annoyed enough to leave such an angry comment.
You can avoid having such a terrible experience and better baking success in the future by:
1-Reading the recipe thoroughly before buying ingredients and beginning to bake.
2-Reaching out to the writer if you have any questions or spot anything that doesn't make sense.
3-Following the recipe exactly without substitutions, unless they are included in the recipe notes.
With Kindest Regards, Colleen
Randy Rogers
I make these all the time when rhubarb looks great at the farmers market here in St. Paul. And when I do I always default back to this recipe. Making these today after picking up a bunch of rhubarb… thanks!
Colleen
Hi Randy. Don't you love rhubarb season? They bars are a favorite, and I'm so glad to here that it's your default recipe. I so appreciate your feedback, thank you! Enjoy your rhubarb blueberry bars!
Kathi
I have frozen rhubarb and frozen blueberries what adjustments should i make in this recipe when using frozen?
Colleen
Hi Kathy, you can use equal amounts of frozen blueberries and rhubarb, just make sure they are thawed first. Happy baking!
Vicky Chin
Looks delicious! I think your homemade version is much better and fresher than Starbucks! We love our blueberries too! Me and my son and easily chomp down a few pounds! Thanks for sharing! And I am going to buy some more blueberries! I love to freeze them at the end of summer so I can enjoy them during the winter months too!
Colleen
Thanks Vicky! I think the homemade version is better, too. Judging by how fast these disappeared, they were good! 🙂
Fareen
I love squares! These look and sound delicious.
Colleen
Thanks Fareen! They are delicious for sure. 🙂
Jessica
I have a TON of fresh rhubarb and a box of blueberries, and now I know exactly what to bake with them! Loving the combination of these fruits plus the oats!
Colleen
Hi Jessica! Isn't it great having all this freshness to deal with? I'm constantly looking for ideas to use all the fresh produce. (not complaining :-))
Justine @ JustineCelina.com
Blueberry and RHUBARB?! That's a combination I haven't yet tried but you've definitely convinced me to give it a go! Have a great weekend Colleen!
Colleen
Justine, yes, they are an amazing combo! I love how the rhubarb tempers the super sweet blueberries. I can think of a lot of other ways to use those two besides these squares. Enjoy your weekend, too!
Nicoletta
I hardly make squares, but now that I've seen these beauties I am excited to make some. Love the flavors! I agree, life is about balance, in life as in food.
Colleen
Hey Nicoletta, You should make these, I think you guys would love them! Keep staying balanced 🙂
Dina
I must make these. My mouth is watering. Also the photography is so good, it's not easy to take good food pics and you are excelling.
Colleen
Thanks Dina! These really are delicious. And thanks for your kind words. I love the photography aspect of blogging, and I'm always learning and striving to improve. So those words are very encouraging. 🙂
Gabrielle @ eyecandypopper
I love squares and I really should make some soon. haha Your recipe sounds yummy, I might try using spelt flour. Yum!
Colleen
Gabby, spelt flour sounds like a great way to make these a lttle less decadent! Thanks for the idea ?