Irresistible Triple Berry Crumb Bars with Brown Butter & Oats: Your New Favorite Summer Treat
There’s something truly magical about a dessert that perfectly balances fruit and crumble, and these Triple Berry Crumb Bars hit every note. I often wonder why we never featured them in the bakeries where I worked, because they are undeniably the kind of treat everyone devours! Imagine a vibrant, super fruity, and intensely jammy filling made from a delightful mix of frozen raspberries, blueberries, and blackberries. This luscious berry layer is perfectly complemented by a sweet, buttery brown sugar oat crumble that literally melts in your mouth with every bite. Think of them as a sophisticated berry cobbler, but in a much more convenient and shareable bar form – truly, they’re even better!
These incredible bars come together surprisingly fast, offering all the delightful flavors of a berry-filled pie without any of the traditional fuss. If you’re a fan of my popular blueberry crumble blondie bars, then prepare to be utterly smitten. These mixed berry crumble bars are destined to earn a permanent, top-tier spot in your summer baking repertoire. Their vibrant color and captivating aroma make them ideal for potlucks, picnics, or simply as a sweet indulgence on a warm afternoon.
Bars are fantastic for their effortless sharability, making them perfect for gatherings, lunchboxes, or a casual dessert. However, on those special occasions when I’m feeling a touch more ambitious and want to impress, I often opt for my comforting brown butter strawberry pie. It delivers that same wonderful, cozy, and intensely fruit-forward flavor, but in a grander, more traditional sliceable format. Both offer a rich, homemade taste, but these berry crumb bars are truly designed for ease and immediate satisfaction.
Unlocking the Perfect Flavor: Key Components of These Berry Bars
What makes these Triple Berry Crumb Bars stand out from the crowd? It’s the harmonious blend of carefully crafted components. The star is undoubtedly the mixed berry jam, cooked to perfection for that ideal “pie-like” consistency. Then there’s the secret weapon: brown butter, lending a depth of nutty flavor to the crumble that elevates it beyond a simple streusel. Finally, the satisfying chew and texture provided by rolled oats in both the crust and topping bring it all together. Let’s dive into how these elements are created.
The Step-by-Step Process for Your Best Berry Bars
1
Craft the irresistible triple berry jam filling. This crucial step is what transforms ordinary frozen berries into a gloriously thick and jammy layer, providing that perfect pie-like bite in every bar. By boiling the berries with sugar, lemon juice, and a cornstarch slurry, we achieve an incredible depth of flavor and ideal consistency, ensuring the filling is never watery.
2
Brown the butter for unparalleled flavor. This step, while simple, adds an incredible depth of nutty, toasted flavor that regular melted butter simply can’t replicate. If you’re new to this technique, don’t worry! My comprehensive how-to brown butter guide will walk you through it effortlessly. Just remember to set it aside to cool slightly before incorporating it into the crumble, as it will be quite hot.
This recipe is undeniably for the crumble enthusiasts, celebrating that glorious buttery, oat-filled texture. However, if you’re seeking something a little more classic, with a soft, cake-like base, my fluffy blueberry crumble cake is precisely what you need. It features a tender cake generously topped with a rich, buttery crumble and bursts with baked blueberries – a true comfort classic!
3
Prepare the rich brown sugar oat crumble. This versatile mixture forms both the sturdy base and the delightful topping of our bars. Simply combine all the dry ingredients with the cooled brown butter until a cohesive, dough-like texture is achieved. The brown sugar adds a lovely caramel note, while the rolled oats contribute to that perfect soft-yet-crispy texture once baked.
4
Press the crumble mixture into the pan, reserving some for the top. It’s essential to press the crumble firmly and evenly into the bottom of your prepared baking pan. This creates a sturdy, delicious base that holds the jammy filling perfectly. Remember to set aside roughly one cup of the mixture – that’s our golden, crunchy topping!
5
Spread the vibrant fruit filling evenly over the crumble base. Once your jam has cooled, carefully spread this rich, fruity layer across the prepared oat shortbread crust. Ensure it reaches all the way to the edges, creating a consistent and generous filling for every bar. The cool jam will hold its shape beautifully as it bakes.
6
Sprinkle the reserved crumble over the berries and bake to golden perfection! Distribute the remaining crumble mixture evenly over the jam. Bake until the edges of the fruit filling are visibly bubbling and the top of the oat crumble turns a beautiful golden brown. This indicates not only doneness but also promises a perfect crisp-tender texture. The aroma filling your kitchen will be absolutely divine!
These Triple Berry Crumb Bars are truly a crowd-pleaser, and I especially love baking them when I’m hosting friends and family. Their convenient bar shape makes serving a breeze, and everyone appreciates a good homemade treat. If you’re looking for more easy-to-share desserts, you absolutely must check out my delightful blueberry pie bars with a lattice top. They capture all the charm and flavor of a classic pie, but in a much more accessible and party-friendly format!
One of the best aspects of these crumb bars is their versatility. While we use frozen mixed berries here, which are incredibly convenient and available year-round, you could easily adapt this recipe to showcase fresh seasonal fruits. Imagine the possibilities with a summer haul of ripe peaches and raspberries, or even a classic apple cinnamon filling in the fall. The brown butter oat crumble is a fantastic base that complements almost any fruit. Plus, using frozen berries often means you can enjoy these delicious bars even when fresh berries are out of season or too expensive.
The beauty of these bars lies in their comforting taste and satisfying texture. The slightly tart, sweet berry filling perfectly complements the rich, nutty oat crumble. Each bite offers a delightful contrast between the tender, jammy fruit and the crispy, buttery topping. They are delightful served at room temperature, perhaps with a dusting of powdered sugar, but truly shine when served slightly warm with a scoop of vanilla bean ice cream or a dollop of fresh whipped cream. These bars also make a surprisingly satisfying breakfast or brunch item, especially alongside a cup of coffee or tea.
If you tried this Triple Berry Crumb Bars recipe or any other delightful creation from my website, please don’t hesitate to share your experience in the comments section below; I absolutely love hearing from you! Your feedback helps others and brings me so much joy. While you’re there, please consider leaving a star rating to let me know how much you enjoyed it! You can also share your baking masterpieces by tagging me on Instagram or Facebook so I can admire your delicious work!
Triple Berry Crumb Bars with Brown Butter & Oats
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Equipment
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metal square 8×8 baking pan
Ingredients
Triple Berry Jam
- 1 cup frozen blackberries
- 1 cup frozen blueberries
- 1/2 cup frozen raspberries
- 2 tablespoons brown sugar, packed
- 2 tablespoons granulated sugar
- 1 teaspoon lemon juice
- 1 tablespoon cornstarch
- 1 tablespoon water
Brown Butter Oat Crumble Crust
- 14 tablespoons unsalted butter
- 1/2 cup granulated sugar
- 1/2 cup brown sugar
- 2 teaspoons vanilla bean paste or extract
- 1 2/3 cup + 1 tablespoon all-purpose flour, *See notes below for measuring*
- 1 cup old fashioned oats
- 1/2 teaspoon fine sea salt
Instructions
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Combine the frozen blackberries, blueberries, raspberries, brown sugar, granulated sugar, and lemon juice in a sturdy pot. Cook this mixture over medium heat for approximately 15-20 minutes, stirring and gently mashing occasionally. Continue cooking until the berries have fully released their delicious juices, the mixture is actively bubbling, and it begins to visibly thicken. Aim to avoid mashing them too much, as leaving some fruit chunks will result in a more delightful, textured jam! In a separate small bowl, whisk together the cornstarch and water to create a smooth slurry. Stir this cornstarch slurry into the simmering berry mixture and cook for an additional 2-3 minutes until the jam reaches your desired thick, luscious consistency. Remove from heat and set aside, allowing it to cool completely before you’re ready to assemble your bars.1 cup (120 g) frozen blackberries, 1 cup (128 g) frozen blueberries, 1/2 cup (50 g) frozen raspberries, 2 tablespoons (25 g) brown sugar, 2 tablespoons (25 g) granulated sugar, 1 teaspoon lemon juice, 1 tablespoon (10 g) cornstarch, 1 tablespoon (15 g) water
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Prepare your baking pan by lining a square 8×8 baking pan with parchment paper. Make sure the parchment extends up all four sides of the pan, creating “slings” that will help you lift the bars out easily after baking. Preheat your oven to 350°F/180°C to ensure it’s ready when you are.
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In a light-colored stainless steel pan (this makes it easier to monitor the color change), melt the unsalted butter over medium heat. Continue to cook, stirring occasionally with a spatula or whisk, until the butter transforms into a rich amber color and you see tiny, fragrant brown milk solids collecting at the bottom of the pan. The aroma will become wonderfully nutty. Immediately scrape all of the browned butter, including the delicious browned bits, into a large heat-safe bowl and set it aside to cool to room temperature. This cooling step is vital to prevent the butter from cooking your other ingredients.14 tablespoons (196 g) unsalted butter
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Once the browned butter has cooled to room temperature, whisk in the granulated sugar, brown sugar, and vanilla bean paste or extract until well combined and smooth. Next, add the all-purpose flour, old fashioned oats, and fine sea salt to the mixture. Stir until all the ingredients are just combined and a cohesive, slightly crumbly dough-like texture forms. This is your versatile oat crumble! Carefully reserve roughly 1 cup (about 130 g) of this dough; this portion will be used for the top crust. Press the remaining crumble mixture firmly and evenly into the bottom of your prepared, parchment-lined baking pan, ensuring it forms a compact and solid base.1/2 cup (100 g) granulated sugar, 1/2 cup (100 g) brown sugar, 2 teaspoons vanilla bean paste or extract, 1 2/3 cup + 1 tablespoon (200 g) all-purpose flour, 1 cup (92 g) old fashioned oats, 1/2 teaspoon fine sea salt
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Evenly spread the cooled, thickened berry filling across the firmly pressed oat crumble base, extending it to the very edges of the pan. Next, take the reserved crumble dough and gently break it into smaller pieces, scattering them evenly over the vibrant berry layer. This creates a beautiful, textural topping. Finally, bake your delightful bars for approximately 35-40 minutes in the preheated oven, or until the berry filling around the edges is bubbling enticingly, and the crumble topping has turned a rich, golden brown. Once baked, patience is key! Allow the bars to cool completely for at least 3-4 hours at room temperature (or chill in the fridge for faster setting) before carefully lifting them out of the pan using the parchment paper slings. Slice them into 16 perfect squares and enjoy your homemade treat!
Notes
Storage: Any leftover Triple Berry Crumb Bars can be stored in an airtight container at room temperature for 2-3 days, maintaining their delicious flavor and texture. For extended freshness, they can also be stored in the refrigerator for up to a week.
Freezing: These bars freeze beautifully! Once completely cooled, wrap individual bars tightly in plastic wrap and then place them in an airtight container or a freezer-safe bag. They can be frozen for up to one month. When you’re ready to enjoy them, simply let the bars defrost at room temperature for a few hours, or warm them gently in the microwave or oven for a fresh-baked feel!
The calorie information provided for the recipe is an estimate. The accuracy of the calories listed is not guaranteed.