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Rhubarb Dump Cake

Rhubarb dump cake is an easy no-mix dessert with a golden, buttery cake topping over a sweet-tart rhubarb filling. You bake rhubarb, sugar, and cake mix in layers for crispy edges and bubbling fruit around the sides.
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Prep Time 10 minutes
Cook Time 45 minutes
cooling 10 minutes
Total Time 1 hour 5 minutes
Servings: 12 servings
Course: Dessert
Cuisine: American
Calories: 360
Ingredients Equipment Method Notes

Ingredients
  

Rhubarb base
  • 6 cups fresh rhubarb diced
  • 1.5 cups sugar
Cake topping
  • 1 box (15.25 oz) yellow cake mix
  • 0.5 cup butter melted
  • 0.5 cup chopped pecans optional
  • 1 vanilla ice cream for serving

Equipment

  • 1 sheet pan

Method
 

Prep and layer
  1. Preheat the oven to 350°F and grease a 9x13-inch baking dish.
  2. Spread the diced fresh rhubarb in an even layer in the bottom of the prepared dish and sprinkle with sugar.
  3. Pour the yellow cake mix evenly over the rhubarb layer without stirring, so the top stays dry and sandy.
  4. Drizzle the melted butter over the cake mix, trying to cover as much surface area as possible so it browns into a crisp topping.
  5. Sprinkle chopped pecans over the top if using for extra crunch.
Bake and cool
  1. Bake at 350°F for 40 to 45 minutes, until the top is golden brown and the rhubarb is bubbling around the edges.
  2. Let the dump cake cool for 10 minutes so the filling thickens slightly before serving.
  3. Serve warm with vanilla ice cream so the melting scoop contrasts with the crispy topping.

Notes

Pro tip: keep the cake mix dry on top—no stirring—so you get those crisp, golden edges and a distinct cake-like crumble. Store leftovers covered in the refrigerator for up to 3 days and rewarm in short bursts in the oven; freezer: yes (freeze cooled portions up to 2 months). For a dairy-free swap, use plant-based butter in the same amount to keep the buttery browning.