This Amazing Rhubarb Dump Cake is a delightful, easy dessert that’s perfect for any occasion. With its sweet and tangy flavor, this cake is a hit with families and friends alike. Made with simple ingredients, you can enjoy a scrumptious cake without any fuss. It’s a fantastic way to highlight the unique taste of rhubarb and add a homemade touch to your table.

Why You’ll Love This Recipe
This recipe is easy to follow and perfect for home cooks of all levels. It requires no special skills or equipment—you simply layer the ingredients and let the oven do the work. It’s great for busy nights or when you have unexpected guests. Plus, the combination of sweet sugar and tart rhubarb creates a mouthwatering flavor that will keep everyone coming back for seconds. With minimal cleanup and maximum satisfaction, this cake quickly becomes a family favorite.
Ingredients You’ll Need
Gather the following ingredients for a delicious rhubarb dump cake:
- 4 cups sliced rhubarb
- 1 cup granulated sugar
- 1 box moist yellow cake mix
- 1 cup cold water
- ¾ cup unsalted butter (melted)
Ingredient Notes, Variations & Simple Swaps
Feel free to get creative with this recipe by adjusting the sweetener. Instead of granulated sugar, you can use brown sugar for a deeper flavor. If you want to add a touch of spice, consider mixing in some cinnamon or nutmeg. For a fruity twist, you can stir in some berries with the rhubarb for added color and taste. Lastly, if you have other types of cake mix on hand, like lemon or vanilla, those can work well too!
Equipment Needed
- 9 by 13-inch baking dish
- Mixing bowl
- Whisk or spoon
How to Make This Recipe
Step 1 – Prepare the Baking Dish
Preheat your oven to 350°F. Grease your 9 by 13-inch baking dish to prevent the cake from sticking. This step is essential for a clean slice and to keep your cake intact.
Step 2 – Layer the Rhubarb and Sugar
Spread the sliced rhubarb evenly across the bottom of the greased baking dish. This creates a juicy layer that will soak into the cake. Next, sprinkle the granulated sugar over the rhubarb. This layer adds sweetness while balancing the tartness of the rhubarb.
Step 3 – Add the Cake Mix and Water
Now, take your yellow cake mix and sprinkle it evenly over the sugar-coated rhubarb. Do not mix; just spread it out. After that, pour cold water over the top of the cake mix. Make sure to cover all areas so the cake cooks evenly.
Step 4 – Drizzle with Melted Butter
Finally, pour the melted butter evenly over the cake mix. The butter helps to create a golden, crispy top as it bakes. Be sure to cover it well for the best flavor.
Step 5 – Bake
Place the assembled cake in the oven and bake for 45-60 minutes. Keep an eye on it, and when the top is browned and a knife comes out clean from the center, it’s ready to come out. Let it cool for a few minutes before serving.

Tips for Perfect Results
To achieve the best outcome with your rhubarb dump cake, consider these tips:
- Use fresh rhubarb for vibrant color and flavor.
- Make sure to evenly distribute the layers for a balanced flavor.
- Allow the cake to cool slightly before slicing to help it set.
- Store leftovers in an airtight container to keep it fresh.
- Pair the cake with whipped cream or vanilla ice cream for a delightful dessert.
Flavor Variations
Take your cake to the next level with these flavor variations:
- Add a splash of vanilla extract to the water for an extra layer of flavor.
- Mix in chopped nuts to the cake mix for added crunch.
- Try adding a layer of sliced strawberries or other fruits along with the rhubarb.
- Include a sprinkle of oats on top for a crumblier texture.
- Use a lemon cake mix instead of yellow for a refreshing twist.
What to Serve With This Recipe
This Amazing Rhubarb Dump Cake pairs wonderfully with various sides and toppings:
- A dollop of whipped cream
- Scoop of vanilla ice cream
- Fresh berries or a fruit salad
- Coffee or herbal tea for a cozy dessert experience
Storage, Make-Ahead & Leftovers
If you have leftovers, store them in the refrigerator in an airtight container. The cake can be enjoyed for a few days. You can also make this cake ahead of time and reheat it in the oven at 350°F for about 10-15 minutes until warm. To freeze, ensure the cake is completely cooled first, then cover tightly and store in a freezer-safe container. Reheat directly from the freezer, adding a few extra minutes to the warming time.
Frequently Asked Questions About This Recipe
Can I use frozen rhubarb?
Yes, you can use frozen rhubarb! Just ensure it’s thawed and drained before using it in this recipe to prevent excess liquid.
How do I know when the cake is done?
The cake is ready when the top is golden brown and a toothpick or knife inserted in the center comes out clean.
Can I double the recipe?
Absolutely! You can double the ingredients and bake it in a larger dish. Just keep an eye on the baking time, as it may vary.
What if I want a gluten-free version?
You can use a gluten-free cake mix to make this recipe suitable for gluten-sensitive individuals.
Can I add more sugar if I like it sweeter?
Certainly! If you prefer a sweeter cake, you can increase the sugar slightly. Just be mindful not to overpower the tart rhubarb flavor.

Amazing Rhubarb Dump Cake
Ingredients
Main Ingredients
- 4 cups sliced rhubarb Use fresh rhubarb for vibrant color and flavor.
- 1 cup granulated sugar Can be substituted with brown sugar for a deeper flavor.
- 1 box moist yellow cake mix Other flavors like lemon or vanilla can also be used.
- 1 cup cold water Optional to add a splash of vanilla extract for flavor.
- ¾ cup unsalted butter (melted) Helps to create a golden, crispy top.
Instructions
Preparation
- Preheat your oven to 350°F and grease a 9 by 13-inch baking dish.
- Spread the sliced rhubarb evenly across the bottom of the baking dish.
- Sprinkle granulated sugar over the rhubarb.
- Sprinkle the yellow cake mix evenly over the sugar-coated rhubarb without mixing.
- Pour cold water evenly over the top of the cake mix.
- Drizzle melted butter evenly over the cake mix.
Baking
- Bake the assembled cake in the oven for 45-60 minutes until the top is browned and a knife comes out clean.
- Let it cool for a few minutes before serving.
