Strawberry Rhubarb Dump Cake

This Strawberry Rhubarb Dump Cake is an easy, fresh treat perfect for springtime. It features fresh rhubarb and strawberry layers without any batter mixing required. Just stack the fruit, sprinkle on strawberry Jell-O powder and dry yellow cake mix, drizzle with melted butter and water, then bake until bubbly and golden. You get a tangy, sweet fruit base under a perfectly crisp cake topping. Serve it warm with vanilla ice cream or chill it and top with whipped cream for an easy crowd-pleaser.

Light, bright, and fuss-free, this Strawberry Rhubarb Dump Cake is a straightforward dessert that celebrates strawberries and rhubarb when they’re at their best. There’s no need to whip up batter — simply layer the fresh fruit, sprinkle a packet of strawberry Jell-O and dry yellow cake mix on top, drizzle melted butter along with a splash of water, and bake until it’s bubbling at the edges and the top crisps to a lovely golden brown.

Keep reading for a simple ingredient list and clear, easy-to-follow steps. I’ll also share handy tips to get the best results, easy twists you can try, and tips on storing any leftovers. Here’s a glimpse of what you’re in for with this dessert:

• A bright, tangy-sweet strawberry and rhubarb filling that’s bursting with fresh flavor.
• A golden, crunchy cake mix topping that requires zero mixing or fuss.
• Minimal prep time with just a handful of ingredients you likely have on hand.
• Flexible serving options—delicious warm with ice cream or chilled with whipped cream.

What Makes It Special

• Super simple: no batter, no mixing, just layer and bake.
• Just six main ingredients plus water means quick and easy shopping.
• Highlights fresh rhubarb and strawberries, offering a bright and tangy-sweet punch.
• Versatile: works beautifully warm with ice cream or chilled with whipped topping.

What You’ll Need

• 4 cups fresh rhubarb, diced
• 2 cups fresh strawberries, sliced
• 3/4 cup granulated sugar (divided as directed below)
• 1 (3 oz) package strawberry Jell-O powder
• 1 (15.25 oz) package dry yellow cake mix
• 1/2 cup unsalted butter, melted
• 1 cup water

Assembling and Baking Instructions

1. Preheat oven to 350°F and spray the bottom of a 9×13-inch baking dish with nonstick spray.
2. Dice 4 cups fresh rhubarb and slice 2 cups fresh strawberries.
3. If using frozen rhubarb, measure it frozen, thaw before assembling, and reduce the added water to 1/2 cup.

4. Spread the diced rhubarb evenly across the bottom of the prepared dish and sprinkle 1/2 cup granulated sugar over it.

   

5. Layer the sliced strawberries over the rhubarb and sprinkle the remaining 1/4 cup granulated sugar evenly over the strawberries.
6. Dust 1 (3 oz) package strawberry Jell-O powder evenly over the fruit.
7. Sprinkle 1 (15.25 oz) package dry yellow cake mix evenly over the fruit layer—do not stir or mix it in.

8. Drizzle 1/2 cup melted unsalted butter evenly over the cake mix, then drizzle 1 cup water (or 1/2 cup if using frozen rhubarb) over the top.

9. Bake at 350°F for 45 to 55 minutes, until the cake mix is lightly browned and the fruit is bubbling at the edges.

10. Remove from the oven and cool to room temperature, then chill in the refrigerator so the filling can set before serving.

    

Pro Tips and Notes

• Use fresh strawberries and rhubarb whenever possible—frozen strawberries release too much liquid and risk making the cake soggy.
• If you do use frozen rhubarb, measure it frozen, thaw before assembling, and reduce the added water to 1/2 cup to keep the texture right.
• Don’t stir the dry cake mix into the fruit layers. The contrast in textures is what makes this dump cake so special.
• Distribute the melted butter and water carefully over the dry cake mix; some parts will stay dry but will crisp up perfectly while baking.
• Letting the cake cool and chill helps the filling thicken and makes cutting easier, but warm servings are just as delightful if you like a looser, saucier dessert.

Flavor Variations and Substitutions

• Use white or butter cake mix instead of yellow cake mix for a slightly different topping flavor.
• Switch out the strawberry Jell-O for another berry-flavored gelatin to alter the fruit taste while staying in the same flavor family.
• Add a teaspoon or two of lemon or orange zest to the fruit for a zesty, fresh twist.
• For extra crunch, sprinkle 1/2 cup chopped pecans or walnuts—or even old-fashioned oats—over the dry cake mix before pouring on the butter.
• Mix 1/2 teaspoon ground cinnamon into the cake mix before topping if you want a subtle warm spice note.

Storage and Reheating Tips

• Refrigerator: Keep any leftover baked cake, covered, in the fridge for 3 to 4 days.
• Freezer: Wrap portions or the whole pan tightly with plastic wrap and foil, then freeze for up to 2 months. Thaw overnight in the fridge before reheating or serving.
• Reheating: Warm single servings in the microwave for 20 to 45 seconds, or reheat the whole pan in a 325°F oven until heated through. Always thaw frozen cake before reheating for best texture.
• Make-ahead: You can prep the cleaned and sliced fruit and store it in the fridge for up to 24 hours before assembling. However, it’s best to bake the assembled cake right away for optimal results.

Common Questions and Answers

• Can I use frozen strawberries or rhubarb? You can use frozen rhubarb if you measure it frozen and thaw before using. Just cut the water down to 1/2 cup since frozen produces extra moisture. However, frozen strawberries aren’t the best choice because they dump too much liquid and make the dessert runny.
• Is chilling required? Chilling helps the fruit filling firm up and makes slicing neater, but you can totally serve the cake warm with ice cream if you prefer that cozy vibe.
• Can I reduce the sugar? Yes! Feel free to cut back on the granulated sugar a bit, though remember the rhubarb is tart on its own, so the sugar and Jell-O powder help balance that tang.
• Is a 9×13 pan necessary? A 9×13-inch pan works best with these ingredient amounts. You can halve the recipe and bake it in an 8×8 or similar smaller pan—just watch for bubbling fruit and a nicely browned top and adjust bake time accordingly.
• Can I make this gluten-free? Absolutely! Just swap in a certified gluten-free yellow cake mix and make sure any gelatin you use is gluten-free too.