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Straight on shot of a stack of blackberry pistachio crumble bars

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


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


  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.