Made with fresh blueberries (or your favorite blueberry jam) and a simple, really delicious crust and crumble topping (with an easy gluten-free option!), these blueberry bars are perfect for both weeknight desserts and weekend gatherings!
The Best Blueberry Crumble Bars
These blueberry bars rock! They are really easy to make (we made sure of that!), include only a handful of fresh, simple ingredients, and are absolutely delicious. The addition of brown sugar in the crust/crumble (same recipe, just different uses!) adds a yummy, rich flavor reminiscent of caramel, and the fresh blueberry jam brightens everything up. They. Are. So. Good. Y’all.
Ingredient Notes and Substitutions
These blueberry bars are made with just a few really simple ingredients! Here’s everything you’ll need for the crust, crumble, and filling:
For the Crust and Crumble
- Flour – to start, you’ll need 1½ cups of flour. All-purpose works here, and so does 1-for-1 gluten-free flour (we use and love THIS one).
- Oats – you’ll also need 1½ cups of rolled oats. If you’re gluten-free, make sure you use certified gluten-free oats.
- Brown Sugar – 1½ cups of brown sugar lends the perfect sweet, caramel-y flavor to the bars.
- Fine Sea Salt – as with most baked goods, this one needs a little bit of salt — a ¼ teaspoon of fine sea salt will do!
- Butter – 9 tablespoons of softened butter (a ½ cup OR 1 stick plus 1 tablespoon) deepens the flavor and helps to hold everything together.
- 1 Egg – 1 egg provides extra strength to the crust and keeps the crust from crumbling.
For the Filling
- Blueberries – 1 pint of blueberries (about 2 cups) gives the bars the tastiest berry flavor! If blueberries aren’t in season, don’t worry — an equal amount of frozen blueberries will do!
- Lemon Juice – 2 tablespoons of lemon juice (the juice from about one lemon) adds a touch of brightness to the filling.
- Sugar – a â…“ cup of sugar sweetens the filling beautifully!
- Cornstarch – 1 tablespoon of cornstarch thickens the filling.
Note: if you’d like to use a blueberry jam instead of reducing blueberries and making your own, feel free to do that! You’ll just need one (about 13-ounce) jar here. The bars will be absolutely delicious either way!
How to Make
Baking can be intimidating, and we totally get that, so we’ve done all of the testing and guesswork for you. Here’s everything you’ll need to do:
- Prep – preheat the oven to 350°F and line a 9×9 pan (or other similarly sized baking dish) with parchment paper.
- Whisk together the dry crust + crumble ingredients – in a large bowl, whisk together the flour, oats, brown sugar, and salt.
- Add the butter + egg to the dry mixture – add the 9 tablespoons of softened butter to the flour mixture and cut it in with a fork, or work the mixture with your hands. Add the egg to the flour mixture, then stir to combine.
- Make the blueberry filling – add the blueberries to a saucepan along with the lemon juice and sugar and let the mixture cook over medium heat for about 10 minutes, until the blueberries have burst. After about 10 minutes, whisk the cornstarch with 2 tablespoons of water, and pour the cornstarch/water slurry into the blueberry mixture. Once the blueberry mixture boils and thickens, remove it from the heat.
- Assemble the bars – press half of the crust mixture into the bottom of the pan, then pour the blueberries over top. Crumble the rest of the crust mixture over the blueberries.
- Bake – bake the bars for 35-40 minutes, until the crust has browned.
- Let cool, then slice and serve – once the bars are cool to the touch, slice and serve them!
How do you know when blueberry bars are done?
You’ll know that the blueberry bars are ready to come out of the oven when the crumble on top has browned and the blueberries have started to burst. YUM!
How do you cut blueberry bars?
It’s really important that you let the bars cool and set before cutting into them, but once they’re cool, the process is easy! You’ll just use a sharp knife to cut all the way through the bars to make even (and if they aren’t totally even, that’s okay too!) blueberry bar squares.
How to Store
While it won’t hurt for your blueberry bars to sit out to cool for a while (or to sit out for a few hours at a party or gathering), we do recommend storing your bars long-term (think: overnight or longer) in the refrigerator. Stored in the fridge, your bars will keep for up to 5 days!
How to Gift
These bars make for the SWEETEST gift (think: housewarming gift, teacher appreciation gift, or just-because-I’m-thinking-about-you gift). While you can absolutely make the bars, slice them, package them up, and gift them that way, we have a thing for DIY baked good gift jars (check out these chocolate chip cookie jars + these hot chocolate jars!) – they’re just so thoughtful! Here’s the step-by-step DIY blueberry jar how-to:
What You’ll Need
- 1 ½ cups of flour
- 1 ½ cups of oats
- 1 ½ cups of brown sugar
- ¼ teaspoon of fine sea salt
- Large glass jar
- Gift tag
- 1, 13-ounce jar of jam
How to Assemble
- In the glass jar, layer your ingredients as follows from the bottom: oats, flour, brown sugar, salt (we recommend using a funnel for the sugar and flour to create even layers). Secure the lid on tight.
- Tie a gift tag around the jar with ribbon and gift alongside the jar of jam!
Frequently Asked Questions
Are blueberry bars supposed to be gooey?
The crust + crumble shouldn’t be gooey, but the blueberry filling should be!
Are blueberries good for you?
YES! Blueberries are lower in sugar than many fruits and are loaded with antioxidants, phytoflavinoids, potassium, and vitamin C, so they’re a really healthy pick.
Can I use a different berry for these bars?
Absolutely! Any berry you love will work great here, and even a mix of different berries would be really delicious!
More Favorite Dessert Recipes
- The Best Strawberry Cake
- 9 Delicious Cake Mix Recipes
- Key Lime Pie Recipe
- Easy Peach Cobbler Dump Cake
- Gluten Free Lemon Bars
- Strawberry Yogurt Pie
- Strawberry Shortcake Sheet Cake
Easy Blueberry Crumble Bar Recipe
Ingredients
For the crust and crumble:
- 1 ½ cups flour
- 1 ½ cups oats
- 1 ½ cups brown sugar
- 1/4 teaspoon fine sea salt
- 9 tablespoons butter 1/2 cup, or 1 stick, plus 1 tablespoon, softened
- 1 egg whisked
For the filling:
- 1 pint blueberries about 2 cups
- 2 tablespoons lemon juice about one lemon
- â…“ cup sugar
- 1 tablespoon cornstarch
Instructions
- Preheat the oven to 350 F and line a 9×9 pan with parchment paper.
- In a large bowl, whisk together the flour, oats, brown sugar, and salt.
- Add the butter to the flour mixture and cut it in with a fork, or work the mixture with your hands. Once the mixture takes on a sand-like texture, mix in the egg until fully combined.
- Add the blueberries to a saucepan along with the lemon juice and sugar, then let cook over medium heat for about 10 minutes, until the blueberries have burst.
- Whisk the cornstarch with two tablespoons water, then pour it into the blueberry mixture. Once the mixture boils and thickens, remove it from heat.
- Press half of the crust mixture into the bottom of the pan, then pour the blueberries over top. Crumble the rest of the mixture over the blueberries.
- Bake for 35-40 minutes, until the crust has browned. Let cool, then slice and serve.
Recipe Notes
- Keep things super easy by skipping the homemade jam and using a 13-ounce jar of store-bought blueberry jam instead.
- For gluten-free: use a cup-for-cup gluten-free flour (we like King Arthur) and gluten-free oats.
Nutrition
Could you substitute almond flour in the crust? Would the measurement stay the same? Thank you!
*Paleo type diet
*too many oats
Sorry sloppy fingers!
I’m sorry but how is this a healthy dessert? I came here because it said fed and fit. I read the bio that said you healed yourself with a paleo type Tibet and all the contributors were hunting for health. Then I see this recipe (which I was excited for because I bought way to many oats and have a bunch of blueberries) but was stopped in my tracks after I saw flour, sugar, butter, and over 400 calories for 1 serving. Am I missing something? Please correct me because I was so excited to find a new healthy blog, but only feel disappointed now.
Hi Tina! All of our recipes are made with better-for-you ingredients, but the website has evolved from Paleo-only recipes to gluten-free recipes made with quality ingredients. I hope this helps!
YUM!!! These turned out perfectly – I used 1:1 GF flour & vegan butter to make them dairy free otherwise followed the recipe exactly and they are a huge hit in our house. Will definitely be making these again in the future!
Awesome! So glad to hear that, Michelle! Thank you for sharing this with us.