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Grandma's Rhubarb Crisp

Grandma's rhubarb crisp is a traditional American comfort food with tender rhubarb bubbling in a sweet syrup and a thick, buttery oat topping. Bake until the topping turns golden-brown and crisp for that scoopable, spoon-friendly texture.
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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: 420
Ingredients Equipment Method Notes

Ingredients
  

For filling
  • 5 cup fresh rhubarb
  • 1.5 cup sugar
  • 3 tbsp all-purpose flour
For topping
  • 1 cup all-purpose flour
  • 1 cup brown sugar
  • 1 cup old-fashioned oats
  • 0.5 cup butter, softened
  • 1 tsp cinnamon

Equipment

  • 1 sheet pan

Method
 

Prep and assemble
  1. Preheat oven to 350°F and grease a 9x13-inch baking dish.
  2. Combine fresh rhubarb, sugar, and all-purpose flour, toss well, then spread the mixture in the prepared dish.
  3. Mix all-purpose flour, brown sugar, old-fashioned oats, softened butter, and cinnamon with a fork until crumbly.
  4. Spread the crumb topping evenly over the rhubarb mixture.
Bake and cool
  1. Bake at 350°F for 40-45 minutes, until the topping is golden brown and the filling is bubbling.
  2. Let the crisp cool for 10 minutes before serving warm.
  3. Serve warm (optional) with vanilla ice cream.

Notes

For the best texture, keep the topping crumbly rather than pressing it into a solid layer—this helps it brown and crisp. Store leftovers covered in the refrigerator up to 4 days; reheat portions in a 325°F oven until warmed through. Freezing is yes: cool fully, freeze tightly wrapped up to 2 months, and thaw overnight in the fridge. For a lighter option, use half the butter in the topping for a slightly less rich crumble.