Here is my favorite rhubarb dump cake recipe, with tangy rhubarb pieces, strawberry gelatin, yellow cake mix, and melted butter that all come together for an easy dessert that practically makes itself.
This rhubarb dump cake is the easiest spring dessert I make, and my family requests it every year when rhubarb season hits. I love that you literally dump everything in a pan and let the oven do all the work. Perfect for when you want something sweet but don’t want to spend all day baking!
Why You’ll Love This Rhubarb Dump Cake
- Super easy preparation – Just dump the ingredients in a pan and bake—no mixing bowls or complicated steps required, making this perfect for beginner bakers or busy weeknights.
- Works with fresh or frozen rhubarb – You can make this dessert year-round without worrying about rhubarb season, and there’s no need to thaw frozen rhubarb first.
- Sweet and tangy flavor – The tart rhubarb pairs perfectly with the sweet jello and cake topping, creating a balanced dessert that’s not too heavy.
- Ready in about an hour – From start to finish, you’ll have a warm, comforting dessert on the table in just over an hour with minimal effort.
What Kind of Rhubarb Should I Use?
Both fresh and frozen rhubarb work perfectly in this dump cake, so use whatever you have on hand or can find at the store. If you’re buying fresh rhubarb, look for firm stalks with a bright color – they can range from pink to deep red, and both are equally good (the color doesn’t affect the flavor). When using frozen rhubarb, there’s no need to thaw it first – just toss it right into your baking dish. Keep in mind that rhubarb stalks can vary in thickness, so just slice them into roughly half-inch pieces for even cooking.
Options for Substitutions
This dump cake is pretty forgiving, so here are some swaps you can make:
- Rhubarb: Fresh or frozen both work great – no need to thaw frozen rhubarb before using. If you can’t find rhubarb, try using sliced strawberries, mixed berries, or even peaches. Just keep the amount around 4 cups.
- Strawberry jello: Any red jello flavor works here – try cherry, raspberry, or strawberry-banana. You can also use sugar-free jello if you’re watching your sugar intake.
- Cake mix: White or yellow cake mix are both fine choices. You could even try vanilla or French vanilla for a slightly different flavor. Just stick with the standard 15.25-ounce box size.
- Butter: Salted butter adds a nice flavor, but unsalted works too – just add a pinch of salt to the top before baking. You can also use margarine in a pinch, though butter gives better flavor.
- Water: The water is essential for this recipe – it helps create the gooey bottom layer, so don’t skip it or substitute it with anything else.
Watch Out for These Mistakes While Baking
The biggest mistake people make with dump cakes is stirring the layers together – resist the urge and keep everything in distinct layers, as the magic happens when the water and butter seep down through the dry cake mix during baking.
Another common error is skipping the chilling step after baking, but those 2 hours in the fridge are crucial for the cake to set properly and develop the right texture, so plan ahead.
Make sure to spread the dry cake mix evenly over the entire surface without any gaps, and drizzle the melted butter in a zigzag pattern to cover as much area as possible – any dry spots won’t bake properly.
Finally, don’t underbake this dessert; the top should be golden brown and crispy, not pale and soft, so if it looks too light at 45 minutes, give it the full hour.
What to Serve With Rhubarb Dump Cake?
This tangy-sweet dessert is begging for a big scoop of vanilla ice cream on top while it’s still warm from the oven. The cold ice cream melting into the warm cake and tart rhubarb is absolutely perfect. If you’re not an ice cream person, a dollop of fresh whipped cream works great too, or even some vanilla yogurt for a breakfast-style treat. I also love serving this at potlucks or family gatherings with a pot of hot coffee, since the tartness of the rhubarb pairs really nicely with a strong cup of joe.
Storage Instructions
Store: Keep your rhubarb dump cake covered with foil or plastic wrap at room temperature for up to 2 days, or in the fridge for up to 5 days. The cake will soften a bit as it sits, but that just makes it more gooey and delicious!
Freeze: This cake freezes really well for up to 3 months. Cut it into individual portions and wrap each piece in plastic wrap, then place in a freezer bag. That way you can grab a piece whenever you’re craving something sweet without thawing the whole thing.
Serve: You can enjoy this cake cold straight from the fridge, at room temperature, or warmed up in the microwave for about 30 seconds. I think it tastes best slightly warm with a scoop of vanilla ice cream on top!
| Preparation Time | 10-15 minutes |
| Cooking Time | 45-60 minutes |
| Total Time | 55-75 minutes |
| Level of Difficulty | Easy |
| Servings | 12 servings |
Estimated Nutrition
Estimated nutrition for the whole recipe (without optional ingredients):
- Calories: 2200-2350
- Protein: 15-20 g
- Fat: 55-65 g
- Carbohydrates: 425-450 g
Ingredients
- 16 oz rhubarb (trimmed and cut into 1-inch pieces)
- 3 oz strawberry gelatin (Jell-O brand recommended)
- 2/3 cup sugar
- 15.25 oz yellow cake mix
- 1/2 cup butter (melted and cooled)
- 1 1/2 cups cold water
- 1 teaspoon vanilla extract
- 1/4 teaspoon salt
Step 1: Prepare the Oven and Dish
Preheat your oven to 350°F and lightly grease a 9×13 inch baking dish with butter or cooking spray.
This ensures your dump cake won’t stick and will bake evenly.
Having the dish ready before you start layering saves time and keeps your ingredients organized.
Step 2: Layer the Rhubarb and Gelatin Mixture
- 16 oz rhubarb
- 3 oz strawberry gelatin
- 2/3 cup sugar
Spread the trimmed rhubarb pieces evenly across the bottom of your prepared baking dish.
Sprinkle the strawberry gelatin powder and sugar directly over the rhubarb, distributing them as evenly as possible.
The gelatin and sugar will create a syrupy base as the rhubarb releases its juice during baking, so don’t worry about mixing—the heat and moisture will combine everything naturally.
Step 3: Add the Cake Mix Layer
- 15.25 oz yellow cake mix
Sprinkle the yellow cake mix evenly over the rhubarb-gelatin mixture, covering it completely.
I like to use my fingers to distribute the mix so it settles into an even layer—this helps the cake bake more uniformly.
Don’t stir or mix; the dry cake mix will absorb the moisture from below and create a tender crumb as it bakes.
Step 4: Pour the Butter and Water Over the Cake
- 1/2 cup butter
- 1 1/2 cups cold water
- 1 teaspoon vanilla extract
- 1/4 teaspoon salt
In a small bowl, whisk together the melted and cooled butter, cold water, vanilla extract, and salt until combined.
Slowly pour this mixture evenly over the entire surface of the dry cake mix.
I recommend pouring in a slow, steady stream to help the liquid distribute evenly rather than pooling in one spot—this ensures the whole cake bakes consistently and rises properly.
Step 5: Bake Until Golden and Set
Place the dish in the preheated 350°F oven and bake for 45 to 60 minutes, until the top is golden brown and the cake is set but still has a slight jiggle in the center when gently shaken.
The exact time depends on your oven, so start checking around 45 minutes.
The rhubarb will have released its juices and created a lovely sauce on the bottom while the cake rises and browns on top.
Step 6: Cool and Serve
Remove the dump cake from the oven and let it cool at room temperature for at least 15-20 minutes before serving—this allows the structure to set slightly and makes it easier to portion.
Serve warm or at room temperature with a dollop of whipped cream or a scoop of vanilla ice cream to complement the tart rhubarb and sweet cake.
Delicious Rhubarb Dump Cake
Ingredients
- 16 oz rhubarb (trimmed and cut into 1-inch pieces)
- 3 oz strawberry gelatin (Jell-O brand recommended)
- 2/3 cup sugar
- 15.25 oz yellow cake mix
- 1/2 cup butter (melted and cooled)
- 1 1/2 cups cold water
- 1 teaspoon vanilla extract
- 1/4 teaspoon salt
Instructions
- Preheat your oven to 350°F and lightly grease a 9x13 inch baking dish with butter or cooking spray. This ensures your dump cake won't stick and will bake evenly. Having the dish ready before you start layering saves time and keeps your ingredients organized.
- Spread the trimmed rhubarb pieces evenly across the bottom of your prepared baking dish. Sprinkle the strawberry gelatin powder and sugar directly over the rhubarb, distributing them as evenly as possible. The gelatin and sugar will create a syrupy base as the rhubarb releases its juice during baking, so don't worry about mixing—the heat and moisture will combine everything naturally.
- Sprinkle the yellow cake mix evenly over the rhubarb-gelatin mixture, covering it completely. I like to use my fingers to distribute the mix so it settles into an even layer—this helps the cake bake more uniformly. Don't stir or mix; the dry cake mix will absorb the moisture from below and create a tender crumb as it bakes.
- In a small bowl, whisk together the melted and cooled butter, cold water, vanilla extract, and salt until combined. Slowly pour this mixture evenly over the entire surface of the dry cake mix. I recommend pouring in a slow, steady stream to help the liquid distribute evenly rather than pooling in one spot—this ensures the whole cake bakes consistently and rises properly.
- Place the dish in the preheated 350°F oven and bake for 45 to 60 minutes, until the top is golden brown and the cake is set but still has a slight jiggle in the center when gently shaken. The exact time depends on your oven, so start checking around 45 minutes. The rhubarb will have released its juices and created a lovely sauce on the bottom while the cake rises and browns on top.
- Remove the dump cake from the oven and let it cool at room temperature for at least 15-20 minutes before serving—this allows the structure to set slightly and makes it easier to portion. Serve warm or at room temperature with a dollop of whipped cream or a scoop of vanilla ice cream to complement the tart rhubarb and sweet cake.
