There’s something nostalgic about a good crumb bar, right? They remind me of lazy weekends growing up—my mom would bake something sweet while we were still in pajamas, and the smell of butter, sugar, and fruit would fill the whole kitchen. These blueberry crumb bars bring back those vibes in the best way, but they’re also just insanely easy to make.
We’re talking about a soft, buttery crust that doubles as the crumb topping (yes, just one dough!), filled with a bright blueberry layer that bakes into this jammy, gooey perfection. You don’t need fresh blueberries either—frozen works just as well. And once they’re baked and cooled, they slice beautifully into bars that are great for sharing (or hoarding—no judgment).
Why You’ll Love These Bars
- Simple pantry ingredients: Nothing fancy here—just basics you probably already have.
- No mixer needed: One bowl, a whisk, and your hands for the crumb topping.
- Bursting with blueberries: Sweet, tart, and juicy, whether you use fresh or frozen fruit.
- Perfect texture: Buttery base + jammy middle + golden crumble on top.
- Freezer-friendly: Make a batch, slice, and stash a few for future snack attacks.
They’re sweet but not cloying, sturdy enough to pack for a picnic or bake sale, and just as welcome on a brunch table as they are on the dessert plate after dinner.
Prep Time and Servings
Total Time:
Prep: 15 minutes
Bake: 40–45 minutes
Cool: At least 1 hour (important for clean slicing!)
Servings:
Makes 12–16 bars
Nutritional Info (Per Bar, based on 16):
Calories: 210
Carbs: 30g
Fat: 9g
Sugar: 15g
Fiber: 2g
Ingredients
For the crust & topping:
- 1 ½ cups all-purpose flour
- 1 ½ cups old-fashioned oats
- ½ cup granulated sugar
- ½ cup light brown sugar, packed
- ½ teaspoon baking powder
- ¼ teaspoon salt
- ¾ cup (1 ½ sticks) unsalted butter, melted
- 1 teaspoon vanilla extract
For the blueberry filling:
- 2 cups blueberries (fresh or frozen—no need to thaw)
- ⅓ cup granulated sugar
- 1 tablespoon lemon juice
- 1 tablespoon cornstarch
- Optional: ½ teaspoon lemon zest for brightness
Step-by-Step Instructions
1. Prep the Pan and Preheat the Oven
- Preheat your oven to 350°F (175°C).
- Line an 8×8 or 9×9-inch baking pan with parchment paper, leaving a little overhang for easy removal.
- Lightly grease the parchment with cooking spray or butter.
2. Make the Crust and Topping
- In a large mixing bowl, combine flour, oats, both sugars, baking powder, and salt.
- Add melted butter and vanilla. Mix with a spatula or your hands until crumbly and evenly moistened.
- Set aside about ¾ cup of the mixture for the topping.
- Press the remaining dough evenly into the bottom of your prepared pan to form the crust. Use your hands or the back of a measuring cup to flatten it firmly.
3. Make the Blueberry Filling
- In a separate bowl, mix the blueberries, sugar, lemon juice, cornstarch, and zest (if using). Stir until the berries are evenly coated.
- Spoon the berry mixture over the crust and spread into an even layer.
4. Add the Crumble Topping
- Sprinkle the reserved crumb mixture evenly over the blueberries. It doesn’t need to cover the entire surface—those juicy purple pockets peeking through are part of the charm.
5. Bake
- Bake for 40–45 minutes, or until the top is golden and the filling is bubbling around the edges.
- Let cool completely in the pan before slicing—this helps the bars hold their shape.
Pro Tip: Pop them in the fridge after cooling to make slicing even easier.
How to Serve
These blueberry crumb bars are super versatile. Try serving them:
- Warm with a scoop of vanilla ice cream
- Chilled straight from the fridge for a firmer bite
- With a dollop of whipped cream or Greek yogurt on top
- Alongside coffee or tea for a cozy afternoon snack
- Packed in lunchboxes or wrapped up for a picnic or road trip
Tips for the Best Crumb Bars
- Don’t skip the cooling time: These need to set before slicing, or you’ll get a delicious (but messy) crumble.
- Use parchment with overhang: It makes lifting the bars out of the pan a breeze.
- Taste your blueberries first: If they’re really sweet, you can reduce the sugar slightly in the filling.
- Want extra crunch? Add ¼ cup chopped pecans or almonds to the topping.
- Double the recipe: Bake in a 9×13-inch pan and increase baking time by about 10 minutes.
Recipe Variations
- Mixed Berry Bars: Use a combo of blueberries, raspberries, and blackberries.
- Cinnamon Touch: Add ½ teaspoon cinnamon to the crust and topping mixture for a cozy twist.
- Gluten-Free: Use a 1:1 gluten-free flour blend and make sure your oats are certified GF.
- Dairy-Free: Swap butter for melted coconut oil or a plant-based butter alternative.
- Lemon-Lovers’ Version: Add extra zest to both the crust and filling for a punchy citrus flavor.
Storage & Freezing
Room Temperature:
Store in an airtight container for up to 2 days.
Fridge:
Keep refrigerated for up to 5 days. The bars firm up and get even better the next day!
Freezer:
Freeze bars individually wrapped in plastic or parchment, then place in a freezer bag or airtight container. Keeps for up to 2 months. Thaw in the fridge or at room temp.
Special Equipment
- 8×8 or 9×9-inch baking dish
- Parchment paper for easy removal
- Mixing bowls
- Measuring cups and spoons
- Spatula or pastry cutter (optional but helpful)
FAQ
Can I use frozen blueberries?
Yes! No need to thaw—just toss them with the sugar and cornstarch and layer them in. You might need to add 5 extra minutes to the bake time.
What’s the best way to slice these cleanly?
Cool completely, refrigerate if possible, then use a sharp knife. Wipe the knife clean between cuts for tidy edges.
Do I have to use oats?
The oats give a great texture, but you can sub extra flour for a smoother, shortbread-like crust and topping.
Can I make these vegan?
Yes—just use a vegan butter alternative like Earth Balance and confirm your sugar is vegan.
How do I make these less sweet?
Cut back slightly on the sugar in the filling (try ¼ cup) or reduce the brown sugar in the crust.
Conclusion
These Blueberry Crumb Bars are everything a dessert should be: buttery, fruity, easy to make, and totally crowd-pleasing. Whether you serve them as an afternoon snack, bring them to a potluck, or just keep a stash in your fridge for sweet emergencies, they’re guaranteed to disappear fast.
If you bake a batch, I’d love to see how they turn out—tag me in your photos or drop a comment with your twist on the recipe!
Print
Blueberry Crumb Bars
- Total Time: 1 hr
Description
These Blueberry Crumb Bars are buttery, crumbly, and bursting with juicy blueberry flavor. With a golden shortbread-like crust and a sweet-tart berry center, they’re perfect for dessert, brunch, or an afternoon snack!
Ingredients
For the crust and topping:
-
1 cup unsalted butter, melted
-
1 cup granulated sugar
-
1 tsp vanilla extract
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½ tsp salt
-
3 cups all-purpose flour
For the blueberry filling:
-
3 cups fresh or frozen blueberries
-
⅓ cup granulated sugar
-
2 tbsp cornstarch
-
1 tbsp lemon juice
-
1 tsp lemon zest (optional)
Instructions
1️⃣ Preheat oven: Set to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper or grease lightly.
2️⃣ Make the crust: In a large bowl, mix melted butter, sugar, vanilla, and salt. Stir in flour until crumbly and combined.
3️⃣ Press the base: Press about ⅔ of the mixture into the bottom of the prepared pan. Set aside the remaining dough for topping.
4️⃣ Prepare the filling: In a bowl, toss blueberries with sugar, cornstarch, lemon juice, and zest until evenly coated.
5️⃣ Layer the bars: Spread the blueberry mixture evenly over the crust. Crumble the reserved dough over the top.
6️⃣ Bake: Bake for 40–45 minutes, or until the top is golden and the berries are bubbly.
7️⃣ Cool and serve: Let cool completely before slicing into bars. Serve as-is or with a scoop of vanilla ice cream.
Notes
-
Use half blueberries and half raspberries for a mixed berry version.
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Store in the fridge for up to 5 days.
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Bars can be frozen and thawed for later treats.
- Prep Time: 15 min
- Cook Time: 45 min
