Mouthwatering Strawberry Rhubarb Dump Cake

When spring rolls around, I get excited about two things: farmers market season and desserts I can throw together without much fuss. Strawberry rhubarb is one of those classic combos that reminds me warmer days are finally here. But let’s be real – I don’t always have time to roll out pie dough or fuss with a lattice top.

That’s where dump cakes come to the rescue. You literally dump the ingredients in a pan and bake. No mixing bowls, no fancy techniques, just layers of fruit, cake mix, and butter that somehow turn into a dessert everyone asks for seconds of. I make this when I want something homemade without spending my whole afternoon in the kitchen.

The tart rhubarb balances out the sweet strawberries, and that crispy, buttery top is exactly what you want with a scoop of vanilla ice cream. Trust me, this one’s going straight into your spring and summer rotation.

What Kind of Rhubarb Should I Use?

Fresh rhubarb is always your best bet for this dump cake, and you’ll find it in grocery stores during spring and early summer. The color of the stalks – whether they’re bright red, pink, or greenish – doesn’t really affect the flavor, so grab whatever looks fresh and firm. If you can’t find fresh rhubarb or it’s out of season, frozen rhubarb works just fine too. Just make sure to thaw it first and drain off any excess liquid so your cake doesn’t end up too watery.

Options for Substitutions

This dump cake is pretty forgiving when it comes to swaps, so here are some options if you need them:

• Rhubarb: Fresh or frozen rhubarb both work great here. If using frozen, don’t thaw it first – just toss it in straight from the freezer. You can also use all strawberries if rhubarb isn’t available, but you might want to add a tablespoon of lemon juice for that tart kick.
• Strawberries: Fresh is ideal, but frozen strawberries work too. Again, no need to thaw them. You could also try raspberries or a berry mix for a different flavor.
• Strawberry gelatin powder: Feel free to use raspberry gelatin, or even cherry if that’s what you have. You can also skip the gelatin entirely and add an extra 1/4 cup of sugar instead, though the color won’t be quite as bright.
• Cake mix: Yellow or white cake mix are both fine. Vanilla cake mix works too. Just stick with one standard box – don’t use mixes with pudding already added, as they can make the texture gummy.
• Butter: Stick with real butter here – it’s what gives the cake that crispy, golden top. Margarine or oil won’t give you the same results.

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 butter and water work their way down through the dry cake mix during baking.

Another common error is cutting your butter into chunks instead of thin slices, which prevents even distribution and can leave you with dry patches of cake mix that never get moistened.

Make sure your rhubarb pieces are cut to a similar size (about 1/2 inch) so they cook evenly, and don’t skip the water – it’s essential for activating the cake mix and creating that signature dump cake texture.

Finally, let the cake cool for at least 15-20 minutes before serving, as it needs time to set up properly and the fruit filling will be extremely hot right out of the oven.

What to Serve With Strawberry Rhubarb Dump Cake?

This sweet and tangy dessert is begging for a big scoop of vanilla ice cream on top – the cold creaminess pairs perfectly with the warm, fruity cake. If you’re not an ice cream person, a dollop of fresh whipped cream or even some Greek yogurt works great too. I love serving this at summer gatherings alongside fresh coffee or iced tea, and it’s also really good the next morning as a breakfast treat (no judgment here!). For a fun presentation, you can add some extra fresh strawberries on the side or a sprinkle of powdered sugar right before serving.

Storage Instructions

Store: Keep any leftover dump cake covered with foil or plastic wrap in the fridge for up to 4 days. The cake will soften a bit as it sits, but it still tastes great! I actually think it’s even better the next day once all the flavors have had time to meld together.

Freeze: You can freeze this cake for up to 3 months in an airtight container or wrapped tightly in plastic wrap and foil. Just know that the texture might be a little softer after thawing, but the flavor will still be there.

Serve: Enjoy your dump cake straight from the fridge if you like it cold, or warm it up in the oven at 350°F for about 10-15 minutes. You can also microwave individual portions for about 30-45 seconds. It’s perfect with a scoop of vanilla ice cream on top!

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 2700-3000
• Protein: 15-20 g
• Fat: 80-95 g
• Carbohydrates: 480-520 g

Ingredients

For the fruit base:

• 4 cups rhubarb (cut into 1-inch pieces)
• 2 cups strawberries (hulled and sliced 1/4-inch thick)
• 1 cup granulated sugar
• 1 tsp cinnamon
• 1 tbsp lemon juice
• 3 oz strawberry gelatin

For the cake topping:

• 15.25 oz yellow cake mix
• 3/4 cup unsalted butter (melted and cooled)
• 3/4 cup water
• 1/4 tsp salt

Step 1: Preheat Oven and Prepare Fruit

• 4 cups rhubarb
• 2 cups strawberries

Preheat your oven to 350°F.

While it heats, prepare the fruit by cutting the rhubarb into 1-inch pieces and hulling and slicing the strawberries into 1/4-inch thick slices.

This prep work ensures everything is ready when you need to layer the dump cake, preventing any unnecessary delays during assembly.

Step 2: Create Spiced Sugar Mixture

• 1 cup granulated sugar
• 1 tsp cinnamon
• 1/4 tsp salt

In a small bowl, whisk together the granulated sugar, cinnamon, and salt until well combined.

Set aside 1/4 cup of this mixture in a separate small bowl—this will be your flavor layer for the strawberries.

I like to reserve the spiced sugar before mixing it all together because it makes the layering process cleaner and ensures the strawberries get their own aromatic boost.

Step 3: Layer Rhubarb and Strawberries in Baking Dish

• rhubarb from Step 1
• strawberries from Step 1
• spiced sugar mixture from Step 2
• 1 tbsp lemon juice

Spread the cut rhubarb evenly in a 9×13 inch baking dish.

Sprinkle the larger portion of the spiced sugar mixture (about 3/4 cup) directly over the rhubarb, then layer the sliced strawberries on top.

Sprinkle the reserved 1/4 cup of spiced sugar mixture over the strawberries, then drizzle the lemon juice over all the fruit.

This layering technique allows the sugar to draw out the fruit juices during baking, creating a flavorful syrup.

Step 4: Add Gelatin and Cake Mix Topping

• 3 oz strawberry gelatin
• 15.25 oz yellow cake mix

Sprinkle the strawberry gelatin powder evenly over the fruit layer, followed by an even distribution of the yellow cake mix.

Don’t stir—let these dry ingredients sit on top of the fruit.

The gelatin will rehydrate as the cake bakes, adding extra fruity flavor and moisture to the topping.

Step 5: Add Butter and Water, Then Bake

• 3/4 cup unsalted butter
• 3/4 cup water

Drizzle the melted and cooled butter evenly over the dry cake mix topping, allowing it to soak into the cake mix gradually.

Pour the water around the edges of the dish and over the top—the water will work with the butter and cake mix to create a cake-like texture as it bakes.

Place the baking dish in the preheated 350°F oven and bake for 50-55 minutes, until the top is golden brown and a toothpick inserted into the cake portion comes out with just a few moist crumbs (not wet fruit).

Step 6: Cool and Serve

Remove the dump cake from the oven and let it cool for at least 15-20 minutes before serving.

I find that waiting a bit allows the cake and fruit layers to set slightly, making it easier to scoop and plate.

The cake will continue to thicken as it cools.

Serve warm or at room temperature with vanilla ice cream or whipped cream if desired.

Mouthwatering Strawberry Rhubarb Dump Cake

Delicious Mouthwatering Strawberry Rhubarb Dump Cake recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 20 minutes mins

Cook Time 45 minutes mins

Total Time 1 hour hr 5 minutes mins

Servings: 10 servings

Calories: 2850

Ingredients Method

Ingredients

  

For the fruit base

• 4 cups rhubarb (cut into 1-inch pieces)
• 2 cups strawberries (hulled and sliced 1/4-inch thick)
• 1 cup granulated sugar
• 1 tsp cinnamon
• 1 tbsp lemon juice
• 3 oz strawberry gelatin

For the cake topping

• 15.25 oz yellow cake mix
• 3/4 cup unsalted butter (melted and cooled)
• 3/4 cup water
• 1/4 tsp salt

Method

 

1. Preheat your oven to 350°F. While it heats, prepare the fruit by cutting the rhubarb into 1-inch pieces and hulling and slicing the strawberries into 1/4-inch thick slices. This prep work ensures everything is ready when you need to layer the dump cake, preventing any unnecessary delays during assembly.
2. In a small bowl, whisk together the granulated sugar, cinnamon, and salt until well combined. Set aside 1/4 cup of this mixture in a separate small bowl—this will be your flavor layer for the strawberries. I like to reserve the spiced sugar before mixing it all together because it makes the layering process cleaner and ensures the strawberries get their own aromatic boost.
3. Spread the cut rhubarb evenly in a 9x13 inch baking dish. Sprinkle the larger portion of the spiced sugar mixture (about 3/4 cup) directly over the rhubarb, then layer the sliced strawberries on top. Sprinkle the reserved 1/4 cup of spiced sugar mixture over the strawberries, then drizzle the lemon juice over all the fruit. This layering technique allows the sugar to draw out the fruit juices during baking, creating a flavorful syrup.
4. Sprinkle the strawberry gelatin powder evenly over the fruit layer, followed by an even distribution of the yellow cake mix. Don't stir—let these dry ingredients sit on top of the fruit. The gelatin will rehydrate as the cake bakes, adding extra fruity flavor and moisture to the topping.
5. Drizzle the melted and cooled butter evenly over the dry cake mix topping, allowing it to soak into the cake mix gradually. Pour the water around the edges of the dish and over the top—the water will work with the butter and cake mix to create a cake-like texture as it bakes. Place the baking dish in the preheated 350°F oven and bake for 50-55 minutes, until the top is golden brown and a toothpick inserted into the cake portion comes out with just a few moist crumbs (not wet fruit).
6. Remove the dump cake from the oven and let it cool for at least 15-20 minutes before serving. I find that waiting a bit allows the cake and fruit layers to set slightly, making it easier to scoop and plate. The cake will continue to thicken as it cools. Serve warm or at room temperature with vanilla ice cream or whipped cream if desired.