Blueberry Crumble Bars
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A buttery shortbread-like base, juicy blueberry filling and crumbly crumble topping – these blueberry crumble bars are so easy and delicious.
**This post was updated May 21, 2024 with new photos and a slightly updated recipe for thicker bars with a juicier blueberry filling**
These blueberry crumble bars have the perfect combination of buttery shortbread, juicy berries and crumble topping. They’re simple to make and way easier to transport than a blueberry crisp or crumble. They can be made with fresh or frozen berries, although using frozen berries will increase the bake time.
I love fruit bars – whether it’s a raspberry oatmeal bar, strawberry crumb bar, or peach pie bar – and these blueberry crumb bars are definitely one of my go to recipes. I love having them with a scoop of ice cream for dessert, and then eating the leftovers the next day with my morning coffee.
Making Blueberry Crumb Bars
This recipe is based off of Deb Perelman’s Blueberry Crumb Bars from Smitten Kitchen. I’m in love with her recipes & writing. The main things were changing here though is the ratio of butter to flour to create a more buttery & shortbread-like base, then making the crumb topping more golden with the addition of brown sugar. I also wanted the bars to be even thicker.
You’ll start by making the blueberry filling. You’ll simply toss together the blueberries along with a little sugar, cornstarch (AKA cornflour in the UK and Australia) and lemon juice. The cornstarch helps to thicken the fruit layer as it bakes so that the bars don’t get too soupy. The lemon juice helps to soften the berries as the bars bake. You won’t really taste the lemon, but it really brings out the flavor of the berries.
Then it’s time to make the dough for the base and topping. First your whisk together the flour, sugar & baking powder in a bowl, then cut in the butter & egg yolk using a pastry cutter or fork. The butter should be cold and cut into cubes before doing this. When you’re done, the mixture will be crumbly – but hold together when you squeeze it in your palms.
Recipe Tip
You’ll notice the recipe calls for COLD butter as opposed to room temperature. Crumbles, shortbreads and scones often call for cold butter because when baking the butter creates steam pockets – which leads to flakier, crumblier goods. Exactly what we’re looking for in crumb bars.
Assembling & Baking the Bars
Then it’s time to assemble the bars. You’ll reserve about 1 cup of the shortbread mixture for the topping. Then press the remaining dough in into the bottom of your prepared pan so that it forms an even layer.
Spoon the blueberry mixture on top of the shortbread base. Note that if there’s a lot of juice at the bottom of the bowl, you can leave it in the bowl.
With the remaining 1 cup of shortbread/crumble mixture, you’ll cut in a little extra flour, granulated sugar and just a touch of brown sugar. This makes the crumb topping even more crumbly and makes the topping golden brown as the bars bake. Then you’ll sprinkle/crumble the topping overtop of the blueberry layer.
The bars will bake for about 50 minutes. When you take them out of the oven you should see the berries bubbling and the top crumble layer will be getting slightly golden in color. Note that if you used frozen berries, they will likely need to bake for an extra 10 minutes or so.
Recipe Tip
The bars will need to fully cool before slicing. Coming from someone who’s as impatient as a 5 year old – I know it’s hard. But cutting into your blueberry crumble bars while they’re still warm causes a big blueberry mess.
The combo of juicy berries, buttery shortbread and crumble topping makes these blueberry crumble bars simply delicious. They recipe is simple to make and perfect if you’re looking for an easy, delicious blueberry dessert.
If you love these blueberry crumble bars, try these other favorite blueberry desserts:
Blueberry Crumble Bars
Equipment
- 8×8 inch (20×20 cm) pan
Ingredients
Blueberry Layer
- 2 cups blueberries (about 250-300 grams if using fresh), fresh or frozen
- 2 teaspoons cornstarch, use 4 teaspoons if using frozen berries
- 1 tablespoon lemon zest
- 1 tablespoon lemon juice, freshly squeezed – do not use lemon juice from a bottle
- 1/4 cup granulated sugar (50 grams)
Shortbread Base & Crumble Topping
- 1 and 1/2 cups all-purpose flour (188 grams) , spooned & leveled
- 1/2 cup granulated sugar (100 grams)
- 1/2 teaspoon baking powder
- 1/4 teaspoon salt
- 3/4 cup unsalted butter (170 grams) , cold, cut into cubes
- 1 large egg yolk, just the yolk – discard the egg white
- 1 tablespoon packed brown sugar
- 1 tablespoon granulated sugar
- 1 tablespoon all-purpose flour
Instructions
- Preheat the oven to 350F (180C) degrees. Line an 8×8 inch square baking pan with aluminium foil or parchment paper so that there's an overhang around the edges.
- In a medium bowl toss together the ingredients for the blueberry layer (blueberries, cornstarch, lemon zest, lemon juice & sugar). Set aside.
- In a separate large bowl whisk together the 1 1/2 cups all-purpose flour, 1/2 cup granulated sugar, baking powder and salt.
- Cut the cubed butter and egg yolk into the flour mixture using a pastry cutter or 2 forks (a pastry cutter will be easier). When finished, the mixture will be slightly crumbly, but
- Reserve 1 cup of the butter mixture for the crumb topping. Press the remaining shortbread mixture into the prepared pan to form the base layer of the bars.
- Spoon the blueberry mixture over top of the shortbread base. You want all of the shortbread to be covered with an even layer of berries. If there's a lot of liquid at the bottom of the bowl (this is more likely to be the case if using frozen berries) do not add the excess liquid to the pan.
- Add the 1 cup of reserved shortbread/crumble mixture back to the bowl. Add in the 1 tablespoon of all-purpose flour, 1 tablespoon of granulated sugar and 1 tablespoon of brown sugar. Use a fork or pastry cutter to incorporate the additional ingredients into the mixture. It will be even crumblier.
- Crumble the remaining dough over the blueberry layer by squeezing it in a fist with your hand, then crumbling it over top.
- Bake in the oven for about 40 minutes, until you see the blueberries bubbling and the crumble layer starting to turn golden. If you used frozen berries, it may need a bit longer to bake.
- Cool bars fully until the pan is room temperature (about 3-4 hours). Then lift the bars out of the pan using the overhang of the parchment paper/aluminum foil. Place on a cutting board and slice using a sharp knife.
Notes
- Nutrition: Details provided are an estimate only and based on 1 bar, assuming the pan is sliced into 9 large squares. You can definitely get 12 smaller bars with this recipe.
- Storage: Store bars in an airtight container in the fridge for up to 4 days.
Nutrition
Recipe adapted from Smitten Kitchen
Honestly this was the best desert I had in a while. When I studied in the U.S, about 5yrs ago apple crumb was my absolute fav! Now I back to Montenegro, my homeland, had a bunch of fresh organic blueberries, followed your steps and it turned out sooo yummi! Adding lemon and lemon zest was such a great idea! thanks for sharing this!
These were super easy to make! I used blueberry pie filling, and they turned out great!
Made these for dessert at a summer BBQ, they were so delish, and super easy. I would definitely recommend – I already sent the recipe to a friend! 🙂
So glad you loved the recipe! Thanks so much for your positive review and sharing the recipe 🙂
Omg thanks for the recipe. Made these last night and they are sooooo good!
If I make these with frozen berries do I need to thaw them first?
You don’t need to thaw the berries first – just make sure they aren’t packed in sugar/syrup. The bake time will just be a bit longer- probably an extra 10 minutes. 🙂
Hi! First of all I’ve already made these twice for my family. My mom called it “the best dessert she’s ever had” and then proceeded to brag to our entire extended family about my baking skills, so thank you for that :). I’m actually in Sweden now and would like to bake them for my host family but we cannot seem to find cornstarch in the store. Is there anything you would recommend in place of that? Thanks!
I’m so glad your family loved the recipe so much! If you can’t find cornstarch, you could replace it with flour or arrowroot powder. I’d use 4 teaspoons of flour instead of 2 teaspoons of cornstarch, or 2 teaspoons of arrowroot powder. Hope this helps! Fiona
I made these with fresh picked blueberries I only added 3tbs of sour cream in the berries. This was easy to make and it’s delicious!! Thank you for sharing your recipe – it’s really good!
Fantastic….a great recipe. Wouldn’t change a thing. Thanks😊
this recipe looks good! too bad we don’t have fresh blueberries here 😞 can i use canned blueberry pie filling instead and just add lemon juice to that?
Hi Fiona,
I am looking for something to bake on a Friday evening to give as a thank you on the following Monday morning, as I will be travelling over the weekend. Will these be ok or will they go soft?
You could store them in an airtight container in the fridge for up to about 3 days, but probably not much longer than that.