Berry Oat Crumble Bars


Sweet summery berries sandwiched between a buttery, oatmeal crust and crumb topping? Yes, please! We’re absolutely head-over-heels right now for these Berry Oat Crumble Bars because they’re like jammy little fruit pies you can hold in your hand (or better yet, one in each hand). They’re the perfect addition to any backyard barbecue or whenever you want to add a little sweetness to your day.

Oat Berry Crumble Bars Stacked

My, oh, my!

I wanted to come up with a witty opener for this post but honestly, all that comes to mind when I think of these Berry Oat Crumble Bars is, ‘My, oh, my!’ Cheesy? Yes. But oh, so accurate. There really are no words for how good these bars are. The sweet, jammy, berry filling is made with just 3 ingredients and we’ve kept the sugar in the crust and crumb topping as low as possible without compromising on the texture but honestly, you’d never know that these are a lower-sugar option because they are just so perfectly, delicious.

They’re also the perfect reason to take advantage of in-season berries!

Oat Berry Crumble Bars Ready to EatThis post contains affiliate links that will not change your price but will share some commission.

Ingredients for Berry Oat Crumble Bars

  • Rolled Oats – You’ll need the old-fashioned kind for these bars (sometimes called just ‘rolled oats’). Quick, instant or steel-cut oats won’t work here
  • Flour – If making these gluten-free, you’ll need to use a gluten-free flour blend (not coconut or almond flour) such as Bob’s Red Mill Gluten-Free 1:1 Flour or King Arthur Flour Gluten-Free Measure-for-Measure Flour. They can also be made with all-purpose flour if you don’t need them to be gluten-free
  • Brown Sugar – Light or dark brown sugar works equally well, with dark brown sugar giving the crust and crumb topping a more molasses-like flavor.
  • Butter – Unsalted butter is the way to go when it comes to baking but if you only have salted butter, just omit the salt from the crust/crumb topping. For a vegan or dairy-free option, we recommend using a vegan butter such as this one or coconut oil
  • Lemon Zest – You just need the zest (it adds a surprising amount of flavor to the crust and crumb topping) so save the lemon to use for another recipe. This Microplane grater gets the job done quickly and will soon become one of your favorite kitchen tools for zesting and grating (citrus, nutmeg, chocolate, garlic, ginger, hard cheeses, and more)
  • Baking Powder – Acts as a leavening agent to give the crust and crumb topping a little lift
  • Cinnamon
  • Salt
  • Vanilla – Be sure to use pure vanilla extract. We love this ethically-sourced Madagascar vanilla
  • Fresh Berries – You can use any combination of berries (strawberries, raspberries, blueberries, or blackberries) – or use just one kind of berry. We have not tested this recipe with frozen berries. 
  • Fruit Juice-Sweetened Jam – Using jam sweetened with fruit juice keeps the added sugars lower in these bars but any jam will work. You can find our favorite fruit juice sweetened brands here and here

Oat Berry Crumble Bars Ready to Serve

How to Make Berry Oat Crumble Bars

These Berry Oat Crumble Bars require a little more work than most of the sweets & treats recipes you’ll find here but trust us, they are worth it. That buttery crust and crumb topping that sandwiches the most perfectly sweet berry filling will make these a dessert you come back to again and again. We promise!

Start by making the crust and crumb topping – which is the same thing. You’ll just make one batch and set aside a little for the topping. For this, you’ll want the butter softened to room temperature so plan ahead by leaving the butter on the counter for a few hours.

Oat Berry Crumble Bars Ingredients Mixed

The crust will need to be par-baked so get the oven preheating before you start whipping up the crust and crumb topping. An 8×8 square baking dish works best for this recipe, but if all you have is a 9×9-inch dish that will work just keep in mind that the bars will be a little thinner.

Lining the pan with parchment paper makes it easy to remove the bars once they’ve chilled so while this seems like a tedious step, we recommend doing it to make your life easier (both when it comes to cutting the bars and cleaning the pan!) And those little clips in the photo below? That keeps your parchment paper from getting in the way when adding the crust and filling to the pan. And yes, they can go into the oven.

While the crust bakes and the crumb topping hangs out in the fridge, it’s time to prepare the berry filling. With just 3 ingredients (berries, jam, and vanilla) it comes together quickly.

Oat Berry Crumble Bars Getting Ready to Bake

When the crust is lightly golden brown on the edges and slightly puffed, it’s time to spread the filling over the warm crust.  Then you just need to sprinkle the cold crumb topping over the berries. You won’t have enough to completely cover all of the berries but that’s okay. You want that berry-jammy goodness to bubble up around those little islands of buttery crumble as you see below. Perfect, right?

Now, for the hardest part. Waiting for your Berry Oat Crumble Bars to cool. It’s tough, we know, but it’s also essential if you want bars. It’s best to let them cool, in the pan, completely at room temperature THEN move them to the fridge to chill awhile longer (preferably overnight for the BEST texture). But if you absolutely cannot wait that long – and who could blame you? These will literally destroy every ounce of self-control you ever thought you had the minute they come out of the oven – you can speed things up by placing them in the freezer for 20 minutes after they’ve reached room temperature.

Oat Berry Crumble Bars Freshly Baked

How to Freeze Berry Oat Crumble Bars

If you’re like us and you want to squirrel away a few of these Berry Oat Crumble Bars for another day (read: don’t want to eat the entire pan in one day) they can be frozen once completely cool. Just slice into bars and place on a baking sheet or plate lined with parchment paper and freeze until solid. Store the frozen bars in a freezer-safe container or bag in the freezer, placing sheets of parchment paper between each if you need to stack them, for up to 1 month.

Good luck forgetting that they’re in your freezer. They are really good frozen. Just saying. 

Oat Berry Crumble Bars Fresh and Ready to Eat

More Bar Recipes You Might Like

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Let’s Get Cookin’

Berry Oat Crumble Bars

  • Author: Jessica Beacom
  • Prep Time: 15 Minutes
  • Cook Time: 30-35 Minutes
  • Total Time: 45-50 Minutes
  • Yield: 16 Bars 1x

Oat Berry Crumble Bars Ready to Eat


For the Crust & Crumb Topping:

For the Filling:

  • 2 ½ cups fresh berries (we used 1 cup each diced strawberries and blueberries + ½ cup raspberries)
  • ½ cup fruit-sweetened strawberry or raspberry jam (such as Crofters, Trader Joe’s or Thrive Market)
  • ½ tsp. pure vanilla extract
  • Pinch of salt


  1. Preheat the oven to 375℉. Line an 8×8-inch square baking pan with parchment paper.
  2. In a bowl, mix together the oats, flour, brown sugar, lemon zest, baking powder, cinnamon, and salt. 
  3. Add the softened butter and vanilla and, using a large spoon or your hands, work the butter into the oat mixture until you get a crumbly dough that will stick together if you pinch it between your fingers. 
  4. Measure out 1 ½ cups of the crust and crumb topping mixture and set aside in the refrigerator. 
  5. Press the remaining crust mixture into the bottom of the parchment paper-lined baking pan using the back of a spoon or spatula or slightly damp fingers. Press the mixture into the pan firmly then use a fork to prick the crust 8-10 times. 
  6. Bake the crust for 10-12 minutes or until the edges look just slightly brown and the crust starts to puff and look set. 
  7. While the crust is baking, wipe out the bowl you used to mix the crust and add the filling ingredients. Stir to combine. 
  8. Remove the crust from the oven then spread the filling in an even layer over the hot crust. Crumble the remaining crust mixture over the top of the filling. 
  9. Bake for 30-35 minutes or until the crust is lightly browned and the filling is bubbling. 
  10. Remove from the oven and place the pan on a wire rack and allow the bars to cool completely then transfer the pan to the fridge for at least 2 hours before cutting.
  11. To cut cooled bars, use the parchment paper to lift the bars onto a cutting board then cut into 16 squares. 
  12. Store leftover bars in a covered container in the fridge for up to 4 days.


  • Do NOT use coconut or almond flour. If making these gluten-free, we recommend Bob’s Red Mill Gluten-Free 1:1 Flour or King Arthur Flour Measure-for-Measure Gluten-Free Flour.
  • Sugar-sweetened jam will work in place of fruit-sweetened jam
  • The crust and crumb topping will brown less with gluten-free flour than it will with all-purpose wheat flour
  • You can use any combination of fresh berries, or use just one kind
  • This recipe has not been tested using frozen berries
  • These will cut, look, and even taste their best if after they’ve cooled at room temperature, you refrigerate them for several hours (even overnight!)


  • Serving Size: 1 bar
  • Calories: 155
  • Sugar: 9g
  • Sodium: 65mg
  • Fat: 7g
  • Saturated Fat: 4g
  • Carbohydrates: 23g
  • Fiber: 2g
  • Protein: 2g

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All photos and content are copyright protected. Please do not use our photos without prior written permission. If you wish to republish this recipe, please rewrite the recipe in your own unique words and link back to the source recipe here on The Real Food Dietitians. Thank you!

Photo Credit: The photos in this blog post were taken by Jess of Plays Well with Butter

About Jessica Beacom

Jessica is a Registered Dietitian Nutritionist living in Boulder, CO with her hubby and two daughters. She’s been described as a ‘real food evangelist’ and loves sharing her knowledge with others to help them break free of the diet mentality and find their own food freedom. In her spare time she enjoys CrossFit, telemark skiing, mountain biking, teaching herself how to play the banjo and camping out under the stars.

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