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Strawberry Marshmallow Crumb Bars Recipe Everyone Loves

Strawberry Marshmallow Crumb Bars

Buttery oat crumb bars layered with thick strawberry preserves and mini marshmallows, then finished with a golden crumb topping. This recipe makes 24 chewy, fruity dessert bars in a 9-by-13-inch pan.
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Prep Time 15 minutes
Cook Time 35 minutes
Total Time 50 minutes
Servings: 24 servings
Ingredients Method Notes

Ingredients
  

Crumb Mixture
  • 2 cups (250 g) all-purpose flour
  • 1 cup (90 g) quick-cooking oats
  • 3/4 cup (150 g) granulated sugar
  • 1/2 teaspoon baking powder
  • 1/2 teaspoon salt
  • 1 cup (226 g) unsalted butter, melted and slightly cooled
  • 1 teaspoon vanilla extract
Filling
  • 1 1/2 cups (about 510 g) strawberry preserves or thick strawberry jam
  • 2 cups (about 100 g) miniature marshmallows

Method
 

Step-by-Step
  1. Heat the oven to 350°F (175°C). Line a 9-by-13-inch baking pan with parchment paper, leaving enough overhang on two sides to lift out the cooled bars.
  2. Whisk together the flour, quick-cooking oats, granulated sugar, baking powder, and salt. Stir in the melted, slightly cooled butter and vanilla until moist, coarse crumbs form.
  3. Press about two-thirds of the crumb mixture firmly into the parchment-lined pan. Bake the base for 10–12 minutes, until lightly set.
  4. Spread the strawberry preserves evenly over the warm crust, leaving a small uncovered border around the edges. Scatter the mini marshmallows over the preserves.
  5. Sprinkle the remaining crumb mixture over the marshmallows. Press some of the reserved crumbs lightly into small clumps for a more evenly browned topping.
  6. Bake for another 25–30 minutes, until the topping is golden brown, the filling bubbles at the edges, and the marshmallows are puffed and lightly browned.
  7. Cool the bars completely in the pan for at least 1 hour. For cleaner slices, refrigerate the cooled pan for 30–60 minutes before lifting the bars out and cutting them into 24 squares.

Notes

Use thick strawberry preserves rather than runny jam to help prevent a soft bottom crust. Store the bars airtight at room temperature for up to 3 days, or refrigerate them for a firmer texture.