strawberry rhubarb crumble squares overhead on parchment

Strawberry Rhubarb Crumble Squares

Course: Dessert
Cuisine: American, Canadian
Keyword: strawberry rhubarb dessert recipes, strawberry rhubarb squares
Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 45 minutes
Servings: 12 squares
Energy: 318 kcal
Author: Jennifer

Easy homemade strawberry rhubarb filling, between an oat crumble base and topping.

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Ingredients

Filling:

  • 1 1/2 cups rhubarb diced, fresh or frozen
  • 1 1/2 cups strawberries fresh or frozen, diced
  • 1 Tbsp lemon juice
  • 3/4 cup white sugar
  • 3 Tbsp cornstarch
  • 1 tsp vanilla or vanilla bean paste

Base/Topping:

  • 1 1/2 cups large flake,old-fashioned rolled oats
  • 1 1/4 cups all-purpose flour
  • 6 Tbsp whole wheat flour
  • 3/4 cups light brown sugar packed
  • 1 tsp baking powder
  • 1/2 tsp coarse kosher salt or 1/4 tsp fine salt
  • 1/2 tsp ground cinnamon
  • 3/4 cup unsalted butter melted

Instructions

  1. In a medium saucepan, stir together the rhubarb, strawberries, lemon juice, white sugar and cornstarch. Heat over medium heat on the stove-top, stirring regularly. When the fruit softens sufficiently, use a potato masher to break it up into smaller pieces. Continue cooking until mixture comes to a boil and thickens, then remove from heat. Stir in vanilla. Allow mixture to cool to lukewarm before proceeding (or can be made ahead and refrigerated. Bring back to room temperature before proceeding).
  2. Heat oven to 350F degrees, and line a 8 x 8-inch pan with parchment paper with overhang on all sides.
  3. In a large bowl, combine oats, flour, whole wheat flour, brown sugar, baking powder, salt and cinnamon. Add melted butter and stir until the mixture forms streusel-like crumbs.
  4. Press 2/3 of crumb mixture into an even layer at bottom of prepared pan. Spread cooled strawberry rhubarb filling in an even layer over crust, then sprinkle remaining crumb mixture evenly over top of jam.
  5. Bake until jam bubbles at edges and streusel is lightly browned, 30 to 35 minutes. Cool completely before slicing into 12 pieces. (*I like to cool to room temperature and then refrigerate a bit before slicing. It just makes for a neater slicing if you'd like to serve it as neat squares).

Recipe Notes

Be sure to read the "Cook's Notes" included with this post, where I share some valuable tips, options, substitutions and variations for this recipe!