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Easy Rhubarb Dump Cake

This easy rhubarb dump cake is one of the simplest spring desserts you can make — just layer, dump, and bake. With a tart rhubarb base and a buttery golden cake topping, it delivers a perfect balance of sweet and tangy flavor with minimal effort.
Prep Time10 minutes
Cook Time45 minutes
Total Time55 minutes
Course: Dessert
Cuisine: American
Keyword: 3 ingredient cake, easy rhubarb recipe, rhubarb dessert, rhubarb dump cake, spring dessert
Servings: 8 servings
Calories: 320kcal
Cost: 5

Equipment

  • 9x13-inch baking dish
  • oven
  • knife for cutting rhubarb
  • measuring cups

Ingredients

  • 5–6 cups chopped rhubarb (fresh or frozen, thawed)
  • 3/4–1 cup granulated sugar
  • 1–2 tbsp cornstarch
  • 1 box (15 oz) yellow cake mix
  • 1/2 cup cold butter, sliced

Instructions

  • Preheat the oven to 350°F (175°C) and grease a 9x13-inch baking dish.
  • Spread the chopped rhubarb evenly across the bottom of the dish. Drain excess liquid if using frozen rhubarb.
  • Sprinkle sugar and cornstarch over the rhubarb. Toss gently and spread evenly.
  • Sprinkle the dry cake mix evenly over the rhubarb layer without mixing.
  • Arrange sliced butter evenly across the surface of the cake mix.
  • Bake uncovered for 40 to 55 minutes until the top is golden brown and the filling is bubbling.
  • Let rest for at least 15 minutes before serving to allow the filling to set.

Notes

Use yellow, lemon, or vanilla cake mix depending on your flavor preference. Always spread the butter evenly to avoid dry patches. Let the cake rest at least 15 minutes before serving for a properly set filling.