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Blueberry Oatmeal Bars
4.5 from 1,017 votes

Blueberry Oatmeal Bars

Blueberry Oatmeal Bars combine a buttery oat and flour crust with a fresh blueberry filling thickened with cornstarch, topped by a crumbly oat topping. The bars balance the sweetness and tartness of blueberries with a firm yet tender oat crust that doubles as a crumb topping. These bars bake into a handheld, sliceable treat that holds together well while offering a fresh fruity layer inside, suitable for breakfasts, snacks, or desserts.

Prep Time
10 mins
Cook Time
55 mins
Cooling Time
30 mins
Total Time
1 hr 35 mins
Servings: 8 servings
Calories: 414 kcal
Course: Baked Goods
Cuisine: American

Ingredients

Crust and Crumble Topping
  • ½ cup butter melted, unsalted
  • 1 cup all-purpose flour
  • ¾ cup old-fashioned oats (don’t use quick cook or instant, they’re finer and behave like flour and will make mixture too dry)
  • ½ cup granulated sugar
  • ¼ cup light brown sugar packed
  • pinch salt optional and to taste
Blueberry Layer
  • 12 ounces blueberries fresh or frozen; I used frozen and didn’t thaw, 2 cups
  • ⅓ cup granulated sugar
  • 2 tablespoons lemon juice
  • 2 teaspoons cornstarch

Instructions

    Cup of Yum
  1. Preheat oven to 350F. Line an 8-inch square pan with aluminum foil and spray with cooking spray; set aside. Lining the pan helps with cleanup and is recommended.
Make the Crust and Crumble Topping
  1. In a large, microwave-safe bowl melt the butter, about 1 minute on high power.
  2. Add the flour, oats, sugars, optional salt, and stir to combine. Mixture will be dry and sandy with some larger, well-formed crumble pieces.
  3. Set 1 heaping cup mixture aside to be sprinkled on later as crumble topping.
  4. Transfer remaining mixture to prepared pan, and using a spatula or your fingers, hard-pack the mixture to create an even, smooth, flat crust; set aside.
Make the Blueberry Layer
  1. In a large mixing bowl (same one used for crust and crumble is okay), add all ingredients and toss to combine. If sugar hasn’t dissolved fully that’s okay because it liquifies while baking.
  2. Evenly distribute blueberry mixture over the crust.
  3. Evenly sprinkle with the reserved heaping 1 cup crumble topping mixture. Before sprinkling, I squeeze the mixture in my palm to encourage bigger crumble pieces to form.
Bake the Bars
  1. Bake for about 55 minutes, or until edges are set and center has just set. Crumble topping should appear set and very pale golden. I used frozen berries without thawing and the pan was very cold going into the oven. If using fresh berries, baking time will be reduced, but I’m not sure by how much, I’d guess at least 10-15 minutes, possibly less. Bars may take longer than 55 minutes if blueberries are very juicy. Watch your bars, not the clock, when evaluating doneness.
  2. Place pan on a wire rack and allow bars to cool for at least 30 minutes before slicing and serving. If you try to slice bars before they’ve cooled completely, they’ll be extremely messy and could fall apart. 

Notes

  • Use old-fashioned oats instead of quick oats to maintain the correct texture; quick oats tend to dry out the mix.
  • For easy cleanup, line your baking pan with aluminum foil and spray with cooking spray before adding the crust mixture.
  • These bars keep well for up to one week at room temperature and may be refrigerated for longer freshness.
  • Freezing the bars extends their shelf life up to six months.

Nutrition Information

Serving 1 Calories 414kcal (21%) Carbohydrates 62g (21%) Protein 4g (8%) Fat 12g (18%) Saturated Fat 7g (35%) Polyunsaturated Fat 4g (24%) Cholesterol 31mg (10%) Sodium 22mg (1%) Fiber 2g (8%) Sugar 33g (66%)

Nutrition Facts

Serving: 8 servings

Amount Per Serving

Calories 414

% Daily Value*

Serving 1
Calories 414kcal 21%
Carbohydrates 62g 21%
Protein 4g 8%
Fat 12g 18%
Saturated Fat 7g 35%
Polyunsaturated Fat 4g 24%
Cholesterol 31mg 10%
Sodium 22mg 1%
Fiber 2g 8%
Sugar 33g 66%

* Percent Daily Values are based on a 2,000 calorie diet.