Blackberry Pistachio Crumble Bars

These Blackberry Pistachio Crumble Bars are the ideal summertime treat – portable, perfectly sweet and salty, and even more delicious with a scoop of vanilla ice cream! They are incredibly simple to make – the base and crumble are made with a mixture of oats, flour, butter, brown sugar, pistachios, and vanilla, and the blackberries cook down to a jam-like consistency beneath the oat crumble topping. They’re all the deliciousness of a homemade pie, without the fuss!

(This post is sponsored by Bob’s Red Mill. Thank you SO much for reading and supporting the brands I love!)

My summertime dessert of choice will forever and always be some type of berry + crumble situation with a scoop of rich vanilla bean ice cream. I typically go with blueberries or strawberries just because they’re delicious and always crowd-pleasers, but I feel like blackberries don’t get enough love. Enter these blackberry pistachio crumble bars! Pistachios in dessert is one of my favorite things because of the sweet and salty/savory, so this entire dessert just makes sense in my mind.

I will choose these crumble bars over brownies or rich chocolate cake any day.

To me they are the perfect balance of sweet, salty, buttery, fruity, and nutty. They have texture from the chewy oats, golden brown crumble, and pistachios. They have caramelly sweetness from the brown sugar, and sweetness/tartness from the blackberries which get tossed with a little lemon juice. And the best part of all, they are SUPER easy to make. Minimal dishes, minimal effort, minimal time involved.

These crumble bars get there chewy oat goodness from my all-time favorite old fashioned oats.

Bob’s oats are my favorite oats to use for all things baking, breakfast, and snacks in my kitchen. In terms of taste and quality, I can always count on their products to be exceptionally good.

Bob’s puts the utmost care and attention into their products, and it shows. I’m not personally gluten free, but a number of people in my life are, and Bob’s Gluten Free Organic Old Fashioned Oats are handled in their dedicated gluten free facility, as well as tested in a state-of-the art laboratory to ensure they meet their strict standards, making them suitable for any kind of dietary restriction or intolerance. In addition to their quality, I love how these oats add a little extra fiber and heart-healthy goodness to these bars. 

These crumble bars can be served warm, room temperature, or even cold! I’ve stored them in the refrigerator for a few days to keep them fresh, and they are every bit as delicious straight out of the fridge.

In order to get them to cut into perfect bars however, they need to be cooled completely. That said, I am never against getting into them warm and serving them a la mode!

Although I have not tried making these with any other berry, I’m sure they’d work with blueberries, raspberries, or a mixture, if that’s what you have on hand. I personally love the blackberries, because they’re extra sweet, super juicy, and slightly tart. They make the perfect filling to these beautiful bars.

The ingredient list to these bars is short and sweet – and it uses mostly pantry staples!

• • Unsalted butter
  • Bob’s Red Mill Gluten Free Organic Old Fashioned Oats
  • All-purpose flour (to keep these gluten free, you can substitute Bob’s Red Mill Gluten Free 1-to-1 Baking Flour)
  • Cinnamon
  • Baking soda
  • Salt
  • Light brown sugar
  • Vanilla
  • Roasted, salted pistachios
  • Blackberries
  • Cornstarch
  • Sugar
  • Lemon juice
  • Flaky sea salt (totally optional, but recommended!)

Again, these are very customizable – you can sub another nut like almonds, walnuts, or hazelnuts, or you can substitute blueberries, strawberries, or a mix of the three!

Here’s a quick rundown on how to make these crumble bars:

• Make the base/crumble topping. Begin by melting your butter, then add your brown sugar and vanilla. In a separate bowl, whisk together your oats, flour, cinnamon, baking soda, and salt. Add the dry ingredients to the wet, folding together with a rubber spatula until combined. Lastly, fold in the pistachios! Let the batter sit for several minutes to allow the flour to absorb all of the wet ingredients. 
• Make the blackberry filling. In a separate bowl, stir together your blackberries, cornstarch, sugar, lemon juice, and a pinch of salt until combined.
• Prep your baking pan. Spray an 8×8 metal or glass baking pan, spray it liberally with nonstick spray, and line it with parchment. Makes for a much easier removal!
• Make the bars. Press about a little more than half of the base/crumble topping evenly into the bottom of the baking dish to form the base. Add the blackberry mixture, and then crumble the remaining base/crumble topping onto the top of the bars.
• And bake! These are perfect for me at about 35 minutes – you just want to see that the crumble is golden brown and the bars are set in the middle.
• Let cool. The hardest part, is to let them cool completely! They will cut much more easily if they are completely cool, otherwise, the bars will not stay together. That said, feel free to eat them warm with a scoop of vanilla ice cream! I also enjoy finishing them with a few pinches of flaky sea salt.

Summer dessert heaven.

Or really anytime heaven. I’ve been known to eat these for breakfast with a cup of coffee or as an afternoon pick-me-up!

If you love these bars, you will enjoy these summer desserts too!

Lavender Blueberry Vanilla Bean Galette
Cherry Bourbon Vanilla Bean Galette
Dark Chocolate Zucchini Cake
Lemon Pistachio Muffins with Lemon Glaze and Candied Pistachios
Lemon Pound Cake with Blueberry Glaze
Brûléed Peanut Butter Banana Pie

Don’t forget to share a photo on Instagram and tag me @spicesinmydna if you make this recipe! Nothing makes me happier than seeing what you create in the kitchen!

5 from 2 votes

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Blackberry Pistachio Crumble Bars

These Blackberry Pistachio Crumble Bars are the ideal summertime treat - portable, perfectly sweet and salty, and even more delicious with a scoop of vanilla ice cream! They are incredibly simple to make - the base and crumble are made with a mixture of oats, flour, butter, brown sugar, pistachios, and vanilla, and the blackberries cook down to a jam-like consistency beneath the oat crumble topping.

Course Breakfast, Dessert, Dessert/Snack, Snack

Cuisine American

Keyword berry crumble bars, blackberry crumble bars, blackberry oat crumble bars, blackberry oatmeal bars, blackberry pie, blackberry pie crumble bars, crumble bars, crumble bars healthy, crumble oat bars

Prep Time 20 minutes

Cook Time 35 minutes

Servings 9 bars

Author Molly | Spices in My DNA

Ingredients

For the base/crumble topping

• 1 1/2 cups Bob's Red Mill Gluten Free Organic Old Fashioned Rolled Oats
• 1 1/4 cups + 1 tablespoon all-purpose flour
• 1/2 teaspoon cinnamon
• 1/2 teaspoon baking soda
• 3/4 teaspoon salt
• 1 cup unsalted butter, melted and cooled
• 1 cup light brown sugar, loosely packed
• 1 teaspoon vanilla extract
• 1/2 cup roasted, salted pistachios, coarsely chopped
• flaky sea salt, optional

For the blackberry filling

• 12 ounces blackberries
• 1 tablespoon cornstarch
• 1 tablespoon sugar
• 1 tablespoon lemon juice
• pinch of salt

Instructions

1. Preheat your oven to 350℉. Spray an 8x8 square metal or glass baking dish with nonstick spray, line with parchment paper, and spray again. Set aside.

2. In a medium mixing bowl, whisk together the oats, flour, cinnamon, baking soda, and salt until combined. In a separate, large mixing bowl, whisk together the melted butter, brown sugar, and vanilla until smooth. Add the dry ingredients to the wet, mixing with a rubber spatula to combine. Fold in the chopped pistachios. Once incorporated, let the dough sit for 5 minutes, to allow the flour to absorb the wet ingredients. If the dough seems too loose after this time, add an additional tablespoon of flour at a time, until mixture resembles wet sand consistency. Set aside.

3. In a medium bowl, stir together the blackberries, cornstarch, sugar, lemon juice, and a pinch of salt until combined. If any of the blackberries are super large, you can cut them/mash them in half with a spoon to create a more uniform filling. Set aside.

4. Press a little over half of the base/crumble mixture into the bottom of the pan, to create an even and smooth "crust". Add the blackberry mixture evenly over the crust. Crumble the remaining base/crumble mixture over top. Bake for 35 minutes, or until crumble is golden brown, and the center is set. Finish with a couple pinches of flaky sea salt, if desired. Let cool completely before cutting into bars.

Recipe Notes

*To keep these bars gluten free, you can substitute Bob's Red Mill Gluten Free 1-to-1 Baking Flour for the all-purpose flour.
*Bars will keep in a sealed container the fridge for 2-3 days.