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Irresistible Rhubarb Crumble Bars Recipe

If you've been searching for the perfect rhubarb crumble bars, this recipe offers a buttery shortbread base, tangy rhubarb compote, and golden oat crumble topping in one easy-to-make dessert perfect for sharing and make-ahead enjoyment.
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Prep Time 20 minutes
Cook Time 30 minutes
Total Time 50 minutes
Servings 12 bars
Calories 310 kcal

Equipment

  • Oven
  • 9-inch square baking pan
  • Large bowl
  • Medium saucepan
  • spoon or glass for pressing dough

Ingredients
  

Base

  • ½ cup cup sugar 100g
  • 2 cups cup all-purpose flour 240g
  • 1 tablespoon tablespoon baking powder
  • ⅔ cup cup salted butter 150g, softened at room temperature
  • 1 large egg

Rhubarb Compote

  • 3½ cups cup diced rhubarb 4–5 long stalks (550g)
  • ⅓ cup cup sugar 65g
  • 1 lemon, zest and juice
  • 2½ teaspoons teaspoon cornstarch

Crumble Topping

  • 1 cup cup old-fashioned rolled oats 100g
  • ½ cup cup sugar 100g
  • 1 teaspoon teaspoon vanilla sugar
  • ½ cup cup salted butter 100g, melted

Instructions
 

Preparation and Base

  • Preheat the oven to 400°F (200°C) and grease a 9-inch square baking pan.
  • Mix sugar, flour, and baking powder. Add softened butter and a pinch of salt, working to coarse crumbs. Stir in egg until dough forms.
  • Press dough evenly into the pan to cover the bottom.

Rhubarb Compote

  • Cook diced rhubarb, sugar, lemon zest and juice over medium heat until bubbling, then stir in cornstarch and simmer 5 minutes until thick.
  • Remove from heat and cool 5 minutes before spreading evenly over the dough base.

Crumble Topping and Baking

  • Mix oats, sugar, vanilla sugar, and melted butter until clumping, then scatter over the rhubarb layer.
  • Bake for 20–25 minutes until topping is golden. Cool completely before slicing.

Notes

For best results, allow bars to cool completely before slicing to ensure clean pieces. Use the back of a lightly floured spoon or the bottom of a glass to press dough evenly. If the topping browns too fast, cover with foil while baking. Vanilla sugar can be substituted with vanilla extract. Use salted butter or add a pinch of salt if using unsalted butter. Lemon zest and juice brighten the filling and balance sweetness.