Mixed Berry Crumble Bars

These Mixed Berry Oat Bars are a perfect crumbly treat. Filled with fresh berries, oats, a hint of cinnamon and only about 10 minutes to prep. The perfect dessert or even brunch treat everyone will love!

This recipe was originally published June 2016 and updated March 2023.

These Mixed Berry Bars are perfect for a treat for summer but thanks to frozen berries, they are the perfect dessert all year long.

When it comes to a good crumble or crisp recipe, I like the crumbly, buttery oat part way more than the fruit section. So these oatmeal bars are my love language. More crumble in every bite. From my Strawberry Crumble to Apple Crumble Bars, you can’t go wrong!

Fruit and oats, right? You really can’t go wrong! I mean, technically that is a good breakfast…

Why You Will Love These Oatmeal Berry Bars:

• Only 10 minutes to prep. This dessert is surprisingly very easy to make. Melt butter, toss everything for the crumble, sweeten the berries and press into pan–that is about it!
• Packed with all the fresh berries. Add any of your favorites or just stick to one. The choice is yours! I typically use blueberries, raspberries and blackberries but sometimes just use whatever I have on hand. Strawberries in the mix are good as well.
• Easily made gluten free. Make sure your oats say certified gluten free and use a 1:1 gluten free all purpose flour and these oat bars are made with no gluten.
• Great for dessert and even a special breakfast! Fruit and oatmeal, right? A special brunch, or even a not so special brunch would be amazing with these berry bars 100%.
• Freezer friendly! We don’t usually have any left in a couple days but I still like to freeze a couple bars for when I have a craving for a berry packed treat.

Recipe Ingredients:

• oats: quick oats are ideal for this recipe as they are smaller and broken down a bit. It allows the bars to hold together so much better. I have made these berry crumble bars with rolled oats and they will still work for sure, I just find the quick oats to have a nicer bar form.
• flour: all purpose flour for best results. You can use an all purpose 1:1 gluten free baking flour if desired!
• brown sugar: light brown sugar is what we use. You could use dark brown if you just have that, the flavor will be a bit different.
• cinnamon: a nice level of spice to give the crumble that traditional cinnamon coziness. Feel free to also add a pinch of nutmeg.
• baking powder: Make sure it is fresh!
• salt: We use sea salt, but table salt will work. If you use salted butter, half the amount of salt in the recipe.
• vanilla: extract if possible for the richest flavor.
• butter: unsalted butter, melted and cooled. You can use salted butter a mentioned above and just half the amount of salt.
• berries: any mixture of berries that you love. Fresh is best but frozen will work as well.
• lemon juice: freshly squeezed is ideal. You can also add some of the lemon zest into the berry mixture.
• sugar: white sugar, and depending on the sweetness or tartness of your berries, you can add or lessen the amount you use here.
• corn starch: This will allow the berry mixture to thicken a bit so that they don’t become watery when baking. You could use a bit of flour if you don’t have any.

How To Make These Berry Bars:

• Combine the berries, corn starch, sugar and lemon juice in a small bowl and set aside. If you are using frozen berries, thaw before mixing. (steps 1 and 2)
• In a separate medium mixing bowl, combine the oats, brown sugar, flour, sea salt, cinnamon, and baking powder. Whisk to combine. (steps 3 and 4)

• Add the melted butter and vanilla to the oat mixture and stir well to combine. The mixture will be nice and crumbly. I like to take a spoonful or two for myself at this point–but not too much because I want the bars too! (steps 5 and 6)
• Press about 2/3 of the oat mixture into an 8×8 inch baking pan that is lined with parchment paper. I sometimes even spritz a little oil to the bottom as well. This makes removing the bars super simple in the end. But that is not necessary. (steps 7 and 8)

• Pour the berry mixture over the pressed oats and spread them out evenly onto the oats. Sprinkle the remaining oat mixture on top of the berries evenly. Pop the berry bars in the oven–you are almost there! (steps 9 and 10)
• Bake for about 28-32 minutes or until the berries are bubbling and the oat mixture on top is golden brown. Remove from the oven and allow to cool completely before cutting. (steps 11 and 12)

Storage Instructions:

These oatmeal berry bars will keep in the refrigerator for up to one week in an air tight container. Allow them to sit out for about 15 minutes before serving to allow them to come to room temperature or warm them up in the microwave.

To freeze, allow the bars to cool completely. Slice them and wrap individually or place in an air tight freezer safe container and freeze for up to 3 months.

Other Desserts to Try:

• Zucchini Bars
• Apple Cranberry Crisp
• No Bake Cookie Butter Cookies
• Nutella Crumble Bars
• Peanut Butter Oatmeal Balls
• No Bake Double Chocolate Raspberry Crumble Bars
• Coconut Almond Chocolate Chunk Skillet Cookie

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