Ingredients
Equipment
Method
- Preheat the oven to 375°F. This initial step is crucial as it ensures your cake bakes evenly. Make sure your oven is at the right temperature before you start.
- Spray a 9×13 pan with baking spray. This prevents the cake from sticking to the pan and makes serving so much easier later on.
- Combine the diced rhubarb, sugar, ½ cup water, cornstarch, and vanilla extract in a large bowl. Stir to combine evenly. This mixture will create a delicious filling for your cake, so make sure all the ingredients are well blended.
- Pour the mixture into your prepared pan. Spread it out evenly so that every slice has a good balance of filling.
- Evenly sprinkle the boxed yellow cake mix over the top of the rhubarb mixture. If needed, you can spread the cake mix to ensure that all the fruit is covered in an even layer. This helps to create a moist, flavorful topping that complements the filling.
- Drizzle the remaining ½ cup of water evenly over the layer of yellow cake mix. This step is key to ensuring that the cake mix hydrates properly during baking.
- Carefully drizzle the melted butter evenly over the water and yellow cake mix. This will help the topping become golden and crispy.
- Bake for 45 minutes or until golden and bubbly. Keep an eye on it as it bakes; the top should turn a lovely golden brown and the filling should be bubbling.
- Remove the rhubarb dump cake from the oven and allow it to rest on the counter for 15 minutes before serving. This resting time enhances the flavor and allows the cake to set, making it easier to cut into squares.
Notes
When buying the cake mix at the grocery store, it is best to pick one that doesn’t have pudding mix in it; check the label to make sure.
You’ll want to use a 9×13-inch cake pan so that the texture and consistency are right. I’ve used an 11x 7-inch pan before, and it turned out a little too thick, which changed the delicious texture of the dump cake.
Rhubarb does need to be peeled or prepared beyond rinsing and cutting off the ends of the stalks. Do not consume any rhubarb leaves as they are toxic.
Fresh rhubarb can sometimes have strings similar to celery that you can just pull off with a sharp paring knife. Usually, it is the larger stalks that have more strings. The smaller, more tender stalks can easily be sliced or diced without removing them.
Oven temperatures vary and may need to be recalibrated periodically to ensure they are accurate. Make sure to keep a close eye on your rhubarb cake as the suggested baking time approaches.