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A white plate holds a square Blueberry-Rhubarb Crumble Bar topped with a scoop of vanilla ice cream and fresh mint, with a colorful cloth in the background.

Blueberry-Rhubarb Crumble Bars

Chef Jenn
Blueberry-Rhubarb Crumble Bars combine tart rhubarb and juicy blueberries in a sweet, buttery oat crumble. With a crisp base, jammy fruit layer, and golden crumb topping, these bars are perfect for summer gatherings, afternoon snacks, or make-ahead desserts. Easy to slice and serve, they're both rustic and irresistible.
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Prep Time 45 minutes
Chill Time 2 hours 45 minutes
Total Time 3 hours 30 minutes
Course Dessert
Cuisine American
Servings 12 servings
Calories 380 kcal

Equipment

Ingredients
  

For the Blueberry-Rhubarb Filling:

  • 1 ½ cups rhubarb sliced
  • 6 ounces blueberries
  • ½ cup brown sugar packed
  • 2 tablespoons cornstarch
  • 2 tablespoons lemon juice
  • 1 tablespoon lemon zest

For The Crumble:

  • 1 teaspoon cinnamon
  • 1 ¼ cups old fashioned oats
  • 1 ⅔ cups all-purpose flour
  • 1 cup brown sugar lightly packed
  • 1/2 teaspoon baking powder
  • ¾ cups unsalted butter softened
  • 1/4 teaspoon salt

Instructions
 

  • Combine rhubarb, blueberries, brown sugar, cornstarch, lemon juice, lemon zest, and cinnamon in a medium saucepan. Cook over medium-low heat, stirring occasionally, for about 15 minutes, or until thickened and jam-like. Set aside to cool slightly.
  • Preheat the oven to 350°F and line an 8x8-inch baking pan with parchment paper, leaving a slight overhang for easy removal.
  • Mix oats, flour, brown sugar, baking powder, and salt in a large bowl. Add the softened butter and use your hands or a pastry cutter to mix until the texture is crumbly. Set aside 1½ cups of this mixture for the topping.
  • Press the rest of the crumble mixture firmly into the bottom of the lined pan using a spatula or your hands. Bake for 10 minutes to set.
  • Spread the cooled fruit filling evenly over the baked crust. Sprinkle the reserved crumble mixture on top.
  • Return the pan to the oven and bake for 25–30 minutes, or until the top is golden and the filling is bubbling around the edges.
  • Let the bars cool to room temperature, then place them in the fridge for 2 to 3 hours to firm up before slicing into clean squares.

Notes

Chef Jenn's Tips

  • Don’t thaw frozen rhubarb before using.
  • Chill completely before cutting to get clean slices.
  • Add cardamom or ginger to the filling if you want a little spice.
  • For crunch, mix chopped nuts into the crumble topping.

Nutrition

Serving: 1barCalories: 380kcalCarbohydrates: 61gProtein: 5gFat: 13gSaturated Fat: 8gPolyunsaturated Fat: 1gMonounsaturated Fat: 3gTrans Fat: 0.5gCholesterol: 31mgSodium: 78mgPotassium: 207mgFiber: 4gSugar: 29gVitamin A: 379IUVitamin C: 4mgCalcium: 68mgIron: 2mg

A Note on Nutritional Information

Nutritional information for this recipe is provided as a courtesy and is calculated based on available online ingredient information. It is only an approximate value. The accuracy of the nutritional information for any recipe on this site cannot be guaranteed.

Keyword blueberry dessert, fruit bars, jam bars, oat crumble, rhubarb crumble bars
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