These mixed berry crumble bars are vegan, gluten-free, and made with one simple oat base that doubles as both the crust and the crumble topping. Juicy, golden, and ready in under an hour.
You might also like: Strawberry Crumble Bars or Easy Lemon Bars
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The moment the farmers markets fill up with fresh berries, I start dreaming about these bars. After my strawberry crumble bars became one of the most popular recipes on the blog, I wanted to make a vegan and gluten-free version using a big mixed handful of whatever berries looked best. These are the result.
What I love most about this recipe is how simple the base is. One oat mixture handles both the crust AND the crumble topping. You mix it once, press two-thirds into the pan, pile on the jammy berry filling, then crumble the rest over the top. That is it. You can pair them with blueberry bars on a dessert platter or bring them to a summer picnic. They travel well and disappear fast.
Best served chilled, though I will be honest: they disappear long before they fully cool down in our house.
Quick Look
- Prep time: 15 minutes
- Cook time: 35 minutes
- Makes: 16 bars
- Pan: 8x8 inch square baking pan
- Dietary: Vegan, gluten-free (use all-purpose flour for a non-gluten-free version)
- Skill level: Easy
Ingredients
For the Crust and Crumble
- 1 cup old-fashioned rolled oats
- ¾ cup Bob's Red Mill 1-to-1 Gluten-free Baking Flour (or all-purpose flour if not gluten-free)
- ½ cup brown sugar, packed
- ½ teaspoon sea salt
- 8 tablespoons vegan butter or margarine, melted (I use Earth Balance Vegan sticks)
- ½ teaspoon vanilla extract
For the Berry Filling
- 2 cups mixed berries (blueberries, raspberries, and strawberries work beautifully)
- 2 tablespoons maple syrup (or your preferred sweetener)
- Zest of one lemon (about 1 tablespoon)
- 2 teaspoons cornstarch
How to Make Mixed Berry Crumble Bars
It starts out with making the no-fuss crust, which is also the crumble topping.
Crumb Topping for Berry Crumble Bars
- Preheat the oven to 375°F. Line an 8x8 inch baking pan with parchment paper and set aside.
- In a medium bowl, stir together the oats, flour, brown sugar, and salt. Add the melted vegan butter and vanilla extract. Stir until everything is combined and clumping together. I like to use my hands here to get nice uneven chunks, which bake up into the best crumble texture.
- Set aside about one-third of the oat mixture for the topping. Press the remaining two-thirds firmly into the prepared pan to form an even crust.
- Bake the crust for 10 to 13 minutes, until the edges just begin to lightly brown. While the crust bakes, make the filling.
Fresh Mixed Berry Filling
- In a small bowl, combine the mixed berries, maple syrup, lemon zest, and cornstarch. Stir gently to coat. If using strawberries, hull them and cut into small pieces first.
- Spoon the berry filling evenly over the warm baked crust. Spread it out with a spatula so you have an even layer.
Add the Crumble and Bake
- Sprinkle the reserved one-third of the oat crumble mixture over the berry filling. Try to cover as much of the surface as you can. Some spots will not be fully covered and that is fine: it means you can see the berry layer bubbling through, which is exactly what you want.
- Bake for 30 to 35 minutes, until the crumble topping is golden brown and the berry filling is bubbling and jammy around the edges. My oven is ready at about 32 minutes. Every oven runs differently so start checking at 28.
- Remove from the oven and let cool completely in the pan at room temperature. For clean slices, transfer to the refrigerator and chill for at least 2 hours before cutting. If you cannot wait that long, the bars are still delicious, just messier to slice. Lift out using the parchment paper overhang and cut into 16 bars.
Recipe Tips
- Pre-bake the crust. I have made these skipping that step and the bars are much better when you bake the crust first. It keeps its structure under the wet berry filling and holds together cleanly when sliced.
- Refrigerate before slicing. The colder the bars, the cleaner the cut. Room temperature bars crumble and fall apart. Give them at least 2 hours in the fridge after they cool, ideally overnight.
- Use your hands for the crumble. A spoon will give you a uniform, sandy texture. Your hands create the irregular chunky clumps that make the crumble topping so satisfying.
- If using frozen berries, do not thaw them first. Add them straight from the freezer and increase the cornstarch to 1 tablespoon to handle the extra moisture.
- Taste your berries before adding sweetener. Very ripe summer berries are already sweet enough. You can reduce or skip the maple syrup entirely depending on how sweet your fruit is.
- The lemon zest is not optional. It makes the filling taste like summer instead of just jam. Zest it fresh and do not substitute lemon juice, which makes the filling too wet.
Serving Suggestions
These bars are incredibly versatile. Here are my favorite ways to serve them:
- Chilled straight from the fridge as a snack or dessert. This is genuinely the best way.
- Warm from the oven with a scoop of vegan vanilla ice cream. The contrast of warm jammy filling and cold ice cream is outstanding.
- As a breakfast bar with a cup of coffee. They are not overly sweet and the oats make them filling enough to function as a meal.
- On a summer dessert platter alongside lemon bars and brownies. They add a beautiful pop of color.
- Pair them with a big bowl of Asian Watermelon Salad for a fruit-forward summer spread.
What to Do with Leftover Berries
This is actually one of my favorite ways to use up berries that are getting close to the end of their prime. Slightly soft berries work better here than in salads because the heat of the oven concentrates the flavor and they go beautifully jammy.
Here are some other great recipes when you have fresh berries to use up:
- Strawberry Crumble Bars (single berry version)
- Blueberry Bars
- Sake Strawberry Apple Bars
- Brown Butter Apple Cinnamon Crumb Bars
These mixed berry crumble bars work with literally any combination of berries you have on hand. Blackberries, boysenberries, currants: if you have it, throw it in.
How to Store Berry Crumble Bars
Store the bars in an airtight container in the refrigerator for up to 4 days. They are actually better on day two once the filling has fully set and the flavors have melded.
You can leave them at room temperature on the first day, covered with foil. But from day two onward they need to go in the fridge.
To freeze: wrap individual bars tightly in plastic wrap and freeze for up to 2 months. Thaw in the refrigerator overnight before serving.
Some other bar recipes to try:
One last thing…I promise!
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Your comments mean the world to me….and I really SMILE when I read them. Thank you so much! XX
Mixed Berry Crumble Bars
Equipment
Ingredients
- For the crust and crumble:
- 1 cup old-fashioned rolled oats
- ¾ cup Bob's Red Mill 1-to-1 Gluten-free Baking Flour or all-purpose if you're not gluten-free
- ½ cup brown sugar packed
- ½ teaspoon salt
- 8 Tablespoons margarine melted I used Earth Balance Vegan sticks, or use unsalted butter if you're not vegan/dairy-free
- ½ teaspoon vanilla extract
- For the filling:
- 2 cups finely mixed berries I used blueberries, raspberries and strawberries
- 2 tablespoons maple syrup or whatever sweetener you like
- Zest of one lemon around 1 tablespoon
- 2 teaspoons cornstarch
Instructions
- Preheat the oven to 375°F and line an 8"x8" baking pan with parchment paper.
- In a medium sized bowl, stir together the oats, flour, brown sugar, and salt. Add in the melted butter (I used Earth Balance Vegan sticks)and vanilla; stir until combined.
- Reserve about ⅓ of the oat mixture for the topping. Spoon in the remaining ⅔ of the crumble mix into your prepared baking pan and press to form a crust.
- Bake for 10-13 minutes, or until the edges of the crust begin to lightly brown. Meanwhile, prep the filling.
- For the filling:
- In a small bowl, stir together the blueberries, raspberries, and strawberries (hull and cut the strawberries in small pieces) with the sugar, lemon zest and cornstarch. Spoon the berry filling over the warm crust and spread evenly with a spatula.
- For the crumble:
- Sprinkle the rest of the crumble mixture over the berry filling and try to cover as much of the berries as you can. There will be spots that aren't completely covered.
- Bake for 30-35 minutes, or until the crust and the crumble are golden and strawberries bubble just a little (mine was ready at just about 32 minutes. Every oven is different).
- Cool completely before trying to remove from the pan. Let chill for a few hours in the refrigerator before slicing or you could dive right in as we did. If you choose to not wait, it will be very tricky to slice them and they will not stay intact.
Nutrition Disclaimer
Please keep in mind that the nutritional information presented below is an approximation and may vary depending on the exact ingredients used.
Notes
- Pre-bake the crust. I have made these skipping that step and the bars are much better when you bake the crust first. It keeps its structure under the wet berry filling and holds together cleanly when sliced.
- Refrigerate before slicing. The colder the bars, the cleaner the cut. Room temperature bars crumble and fall apart. Give them at least 2 hours in the fridge after they cool, ideally overnight.
Nutrition
FAQ's
Yes. Add frozen berries directly from the freezer without thawing first. Increase the cornstarch from 2 teaspoons to 1 tablespoon to account for the extra moisture that frozen berries release as they bake. The texture of the filling is slightly softer with frozen berries but the flavor is still great.
Two things make the biggest difference: pre-baking the crust before adding the filling, and chilling the bars fully before slicing. If you cut them while still warm they will fall apart no matter what. Give them at least 2 hours in the refrigerator after they reach room temperature and they will slice cleanly.
Up to 4 days in the refrigerator in an airtight container. They also freeze well for up to 2 months when individually wrapped. The texture is best on days one through three.
Arrowroot powder or tapioca flour both work as 1-to-1 substitutes for the cornstarch. Both thicken the filling in a similar way. If you use tapioca flour, the filling may have a slightly glossier finish, which is actually very pretty.
Can I make these bars with regular all-purpose flour?
Absolutely. Replace the gluten-free baking flour with the same amount of all-purpose flour. Everything else stays the same. The result is equally delicious and the texture is very similar.
AMAZING bars! I love that I can add blueberries or strawberries!