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Homemade Rhubarb Crunch

Homemade rhubarb crunch is a classic American spring dessert with sweet rhubarb filling and an extra-thick crunchy oat topping. You’ll bake until the topping turns deep golden and crispy, then cool briefly for a warm, set slice.
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Prep Time 15 minutes
Cook Time 45 minutes
cooling 10 minutes
Total Time 1 hour 10 minutes
Servings: 8 servings
Course: Dessert
Cuisine: American
Calories: 360
Ingredients Equipment Method Notes

Ingredients
  

Filling
  • 5 cup fresh rhubarb
  • 1.25 cup sugar
  • 0.25 cup all-purpose flour
  • 1 tsp vanilla extract
Topping
  • 1.5 cup old-fashioned oats
  • 1 cup all-purpose flour
  • 1 cup brown sugar
  • 0.75 cup butter melted
  • 1 tsp cinnamon
  • 0.5 tsp salt

Equipment

  • 1 sheet pan

Method
 

Prep and fill
  1. Preheat the oven to 350°F and butter a 9x13-inch baking dish. Grease the entire base and sides so the rhubarb crunch releases cleanly.
  2. Combine fresh rhubarb, sugar, all-purpose flour, and vanilla extract, then spread the mixture in the prepared baking dish. Level it into an even layer so the topping bakes uniformly.
Make the oat topping and bake
  1. Mix old-fashioned oats, all-purpose flour, brown sugar, melted butter, cinnamon, and salt until well combined. The mixture should look evenly coated and crumbly.
  2. Spread the topping thickly and evenly over the rhubarb. Press lightly so it forms a connected crunchy layer during baking.
  3. Bake for 40-45 minutes at 350°F until the topping is deep golden and crispy. Look for crisp edges and a browned top, with bubbling rhubarb visible near the sides.
Cool and serve
  1. Cool for 10 minutes before serving warm. This short rest helps the filling set and prevents the crunchy topping from sliding.

Notes

For best crunch, let the baked rhubarb crunch cool for the full 10 minutes so the filling thickens before you scoop. Store leftovers covered in the refrigerator for up to 4 days; rewarm portions in a 325°F oven for 8-12 minutes to re-crisp the topping. Freezing is not recommended because the oat topping can lose crunch after thawing. If you want a lighter option, use a 1:1 baking sugar substitute for the sugar in the filling.