Easy Rhubarb Crisp with Yellow Cake Mix

Finding a simple dessert that actually tastes homemade when you’re short on time can feel nearly impossible. After all, impressive desserts usually require precise measurements, complicated techniques, and hours of your day, and things get even trickier when you’re trying to use up seasonal produce before it goes bad.

Luckily, this rhubarb crisp with yellow cake mix checks all the boxes: it’s sweet and satisfying, requires minimal effort and prep work, and makes the most of fresh rhubarb without any fussy steps.

What Kind of Rhubarb Should I Use?

You can use fresh or frozen rhubarb for this crisp, and both will turn out great. If you’re buying fresh rhubarb, look for stalks that are firm and crisp, not limp or bendy. The color can range from light pink to deep red, and while the red stalks look prettier, the green ones are just as tasty. If you’re using frozen rhubarb, there’s no need to thaw it first – just toss it right into your baking dish with the other ingredients. Keep in mind that rhubarb can be quite tart on its own, which is why we’re adding sugar to balance it out and create that perfect sweet-tart flavor.

Options for Substitutions

This simple dessert is pretty forgiving when it comes to swaps:

• Strawberry rhubarb mix: If you can’t find the pre-made mix, use 6 cups chopped rhubarb and 2 cups sliced strawberries. You can also use just rhubarb if that’s all you have – you might want to add an extra tablespoon or two of sugar since strawberries add natural sweetness.
• Yellow cake mix: White or vanilla cake mix works just as well here. Some people even like using spice cake mix for a warmer flavor, though that changes the taste quite a bit.
• Butter: You can use margarine in place of butter, though the flavor won’t be quite as rich. Coconut oil also works if you melt it first, but it will add a slight coconut taste.
• Sugar: Feel free to adjust the sugar amount based on how tart your rhubarb is and your personal preference. You can use brown sugar instead of white for a deeper, caramel-like sweetness.
• Cornstarch: If you’re out of cornstarch, use 2 tablespoons of flour or tapioca starch instead to thicken the fruit filling.

Watch Out for These Mistakes While Baking

The biggest mistake when making rhubarb crisp is not mixing the cornstarch thoroughly with the fruit and sugar, which can lead to uneven thickening and a runny filling – make sure everything is well combined before transferring to your baking dish.

Another common error is not cutting the butter into the cake mix enough, so work it in until you get pea-sized crumbles that will create that perfect crispy topping instead of large clumps.

To avoid a burnt top with undercooked fruit, tent the casserole with foil after 25 minutes if the topping is browning too quickly, and always check that the fruit is bubbling around the edges before removing from the oven.

For extra flavor, try adding a pinch of cinnamon to your cake mix topping or a splash of vanilla to the fruit mixture before baking.

What to Serve With Rhubarb Crisp?

The best way to enjoy rhubarb crisp is warm from the oven with a big scoop of vanilla ice cream melting on top. I also love serving it with a dollop of fresh whipped cream or even a spoonful of Greek yogurt if you want something a little tangy to balance out the sweetness. For a complete dessert spread, pair it with hot coffee or cold milk, and if you’re serving it for brunch, it goes great alongside scrambled eggs and bacon. Some people even like adding a drizzle of caramel sauce over the top for extra indulgence.

Storage Instructions

Store: Keep your rhubarb crisp covered with foil or plastic wrap in the fridge for up to 4 days. It actually tastes amazing cold straight from the fridge the next day – I sometimes eat it for breakfast with a dollop of yogurt!

Freeze: This crisp freezes really well for up to 3 months. Let it cool completely, then wrap it tightly in plastic wrap and foil before freezing. You can freeze the whole pan or cut it into individual portions for easy grab-and-go desserts.

Warm Up: To enjoy it warm again, just pop it in a 350°F oven for about 15-20 minutes if it’s from the fridge, or 30-40 minutes if frozen. You can also microwave individual portions for about a minute, though the topping won’t be quite as crispy.

Estimated Nutrition

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

• Calories: 2900-3200
• Protein: 20-28 g
• Fat: 70-90 g
• Carbohydrates: 530-600 g

Ingredients

For the filling:

• 8 cups strawberry rhubarb mix (cut into 1-inch pieces to ensure even baking)
• 3/4 cup sugar
• 1.5 tbsp cornstarch (I use Argo for a perfectly thickened sauce)

For the topping:

• 1 box yellow cake mix (I prefer Betty Crocker Super Moist for the best flavor)
• 3/4 cup unsalted butter (melted and cooled slightly for a crispier crumble)

Step 1: Preheat and Prepare the Fruit Filling

• 8 cups strawberry rhubarb mix
• 3/4 cup sugar
• 1.5 tbsp cornstarch

Preheat your oven to 350°F.

While it heats, combine the strawberry rhubarb mix, sugar, and cornstarch in a large bowl.

Toss gently but thoroughly until all the fruit pieces are evenly coated with the sugar-cornstarch mixture—this ensures the filling will thicken properly and cook evenly.

The cornstarch will absorb the fruit’s juices and create a beautifully thickened sauce.

Step 2: Create the Cake Mix Crumble Topping

• 1 box yellow cake mix
• 3/4 cup unsalted butter

Pour the yellow cake mix into a medium bowl.

Add the melted and slightly cooled butter, then use a fork to break up the dry mix and distribute the butter evenly throughout.

Work until you have a coarse, crumbly texture—it should resemble wet sand.

I like to use slightly cooled butter rather than hot because it creates a crispier, more distinct crumble topping that doesn’t turn muddy or compacted during baking.

Step 3: Assemble and Bake the Crisp

• fruit filling from Step 1
• cake mix crumble from Step 2

Spread the fruit filling from Step 1 into a 9×13 inch baking dish, spreading it into an even layer.

Scatter the cake mix crumble from Step 2 evenly over the fruit, leaving some small gaps so steam can escape and the fruit stays tender rather than mushy.

Bake at 350°F for 35-45 minutes, until the topping is golden brown and the fruit filling begins to bubble slightly around the edges—this visual cue tells you the filling has thickened and the flavors have melded together.

Step 4: Cool Slightly and Serve

Remove the crisp from the oven and let it rest for 5-10 minutes before serving.

This allows the filling to set slightly and makes serving much cleaner.

Scoop into bowls and top with a generous dollop of whipped cream or a scoop of vanilla ice cream—the cold dairy is essential here as it balances the tartness of the rhubarb and creates the perfect textural contrast with the warm, crispy topping.

Easy Rhubarb Crisp with Yellow Cake Mix

Delicious Easy Rhubarb Crisp with Yellow Cake Mix recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 35 minutes mins

Total Time 52 minutes mins

Servings 8 servings

Calories 3050 kcal

Ingredients

  

For the filling::

• 8 cups strawberry rhubarb mix (cut into 1-inch pieces to ensure even baking)
• 3/4 cup sugar
• 1.5 tbsp cornstarch (I use Argo for a perfectly thickened sauce)

For the topping::

• 1 box yellow cake mix (I prefer Betty Crocker Super Moist for the best flavor)
• 3/4 cup unsalted butter (melted and cooled slightly for a crispier crumble)

Instructions

 

• Preheat your oven to 350°F. While it heats, combine the strawberry rhubarb mix, sugar, and cornstarch in a large bowl. Toss gently but thoroughly until all the fruit pieces are evenly coated with the sugar-cornstarch mixture—this ensures the filling will thicken properly and cook evenly. The cornstarch will absorb the fruit's juices and create a beautifully thickened sauce.
• Pour the yellow cake mix into a medium bowl. Add the melted and slightly cooled butter, then use a fork to break up the dry mix and distribute the butter evenly throughout. Work until you have a coarse, crumbly texture—it should resemble wet sand. I like to use slightly cooled butter rather than hot because it creates a crispier, more distinct crumble topping that doesn't turn muddy or compacted during baking.
• Spread the fruit filling from Step 1 into a 9x13 inch baking dish, spreading it into an even layer. Scatter the cake mix crumble from Step 2 evenly over the fruit, leaving some small gaps so steam can escape and the fruit stays tender rather than mushy. Bake at 350°F for 35-45 minutes, until the topping is golden brown and the fruit filling begins to bubble slightly around the edges—this visual cue tells you the filling has thickened and the flavors have melded together.
• Remove the crisp from the oven and let it rest for 5-10 minutes before serving. This allows the filling to set slightly and makes serving much cleaner. Scoop into bowls and top with a generous dollop of whipped cream or a scoop of vanilla ice cream—the cold dairy is essential here as it balances the tartness of the rhubarb and creates the perfect textural contrast with the warm, crispy topping.