4-Ingredient Rhubarb Dump Cake
This rhubarb dump cake is the kind of dessert you throw together when the rhubarb patch is overflowing and you need something sweet with almost no effort.
A layer of tart rhubarb, a sprinkle of sugar, cake mix, and butter. It bakes up with a crisp top and a jammy, tangy fruit layer underneath.
What Makes This Dump Cake So Good
The top gets golden and crisp, while the rhubarb beneath turns soft and just sweet enough. No mixer, no creaming butter and sugar, just layering and baking.
I keep coming back to this one because it uses up a lot of rhubarb and tastes like a cobbler without the fuss. The cake mix soaks up the buttery juices and turns into something almost caramelized.
Ingredients
- 4 cups chopped rhubarb (about 1 lb): trim and cut into 1/2-inch pieces
- 3/4 cup granulated sugar: adjust based on how tart your rhubarb is
- 1 box (15.25 oz) yellow cake mix: any brand, do not prepare as directed on the box
- 1/2 cup (1 stick) unsalted butter, melted: salted works, just skip any extra salt
Variations / Substitutions
- Swap the fruit: chopped strawberries or peeled peaches work well here, keep the same total volume.
- Change the cake mix: vanilla, white, or even spice cake mix all give good results.
- Use a different fat: melted coconut oil replaces the butter 1:1 for a dairy-free version.
- Add a little spice: sprinkle 1/2 tsp cinnamon or a pinch of nutmeg over the fruit before adding the cake mix.
If you love fruit crisps, try my Strawberry Rhubarb Crisp.
How to Make Rhubarb Dump Cake
Step 1: Toss the Rhubarb and Sugar
Preheat the oven to 350°F (175°C). In a 9×13-inch baking dish (no need to grease it), toss the 4 cups chopped rhubarb with the 3/4 cup sugar until the pieces are coated.
The sugar will start pulling moisture from the rhubarb, creating a little syrupy puddle at the bottom of the dish. Spread the mixture into an even layer.
Step 2: Top with Cake Mix and Butter
Sprinkle the box of cake mix evenly over the sugared rhubarb. Slowly drizzle the 1/2 cup melted butter all over the top, trying to cover as much of the dry mix as you can. Let the dish sit for 5 minutes so the butter can start soaking into the mix.
You will see some dry patches, and that is okay. The fruit juices will steam up and moisten everything as it bakes. Do not stir the layers.
Step 3: Bake Until Golden
Bake for 40 to 45 minutes, until the top is deep golden brown and the fruit is bubbling around the edges.
Your kitchen will smell like butter and caramelized sugar. If the top browns too quickly, tent it loosely with foil during the last 10 minutes.
Step 4: Cool Slightly and Serve
Let the cake cool in the pan on a wire rack for at least 15 minutes. Spoon it into bowls while still warm, scooping through the crisp topping and the jammy rhubarb layer underneath.
The top shatters a little under the spoon, and the rhubarb is sweet-tart and soft. A scoop of vanilla ice cream melting over the top is hard to beat.
A Few Notes Before You Start
- If your rhubarb is extra tart, bump the sugar up to 1 cup.
- For a nutty crunch, scatter 1/2 cup chopped pecans over the cake mix before pouring the butter.
- Using frozen rhubarb? No need to thaw it first. Just add 5 to 10 minutes to the bake time and watch for bubbling around the edges.
Bake times by pan size:
| Pan | Time |
|---|---|
| 9×13-inch | 40–45 mins |
| 8×8-inch | 45–50 mins |
Storing Leftover Dump Cake
- Refrigerate: cover the dish and refrigerate for up to 4 days. The topping softens but tastes just as good.
- Reheating: warm individual portions in the microwave for about 30 seconds, or put the whole dish back in a 300°F oven until heated through.
- Serve cold: chilled leftovers are nice for breakfast with a spoonful of yogurt.
What to Serve With Rhubarb Dump Cake
Vanilla ice cream is the classic, the cold cream pulling against the warm, tangy fruit. A cloud of lightly sweetened whipped cream or a drizzle of heavy cream works just as well. For a little tang, add a dollop of crème fraîche.
Frequently Asked Questions
Why is my dump cake runny?
A little softness is normal, but too much liquid means your rhubarb released a lot of juice. Next time, toss the fruit with 2 tablespoons of cornstarch along with the sugar before baking.
Can I halve the recipe?
Yes. Use an 8×8-inch dish, half of all the ingredients, and bake for 30 to 35 minutes. The smaller amount works nicely for two or three people.
Do I need to grease the baking dish?
No. The butter from the topping is enough to keep it from sticking, especially in a glass or ceramic dish.
Can I use a sugar substitute?
A granular baking sweetener that measures 1:1 for sugar will work. The top may not brown quite as deeply, but the flavor stays good.
Rhubarb Dump Cake Recipe
Ingredients
Method
- Preheat oven to 350°F (175°C). Toss rhubarb and sugar in a 9×13-inch baking dish, spread evenly.
- Sprinkle cake mix over fruit, then drizzle melted butter on top. Let sit 5 minutes, do not stir.
- Bake 40–45 minutes until golden and bubbling. Tent with foil if browning too fast.
- Cool at least 15 minutes, then spoon into bowls. Serve warm with ice cream if you like.
