Step 1

Preheat the oven to 350 degrees. Lightly spray a 13- by 9-inch baking dish with cooking spray.

Step 2

Arrange the rhubarb in an even layer in the bottom of the baking dish. Sprinkle the jello over that, then top with the sugar.

Step 3

Sprinkle the yellow cake mix powder over all of that, then top with the melted butter and the cold water. Bake for 45 minutes to an hour, until the top is lightly browned and the rhubarb is bubbling.

Step 4

It’s possible to serve the dump cake warm but it’s MUCH easier to serve if you chill it for a couple of hours, until it sets up a bit. Serve with whipped cream or ice cream if desired.

Step 5

Uneaten cake can be stored in the fridge, covered, for up to 4 days or frozen (tightly wrapped) for up to 2 months.