Technically this recipe creates an upside-down cake, but I found the mess factor to exceed any presentational value. Therefore, this is now Rhubarb Right-Side-Up Cake, which is perhaps my favorite method to use rhubarb. This relatively healthy dessert has a nice balance of sweet and tart.
Rhubarb Right-Side-Up Cake
5 cups fresh or frozen rhubarb (1/2-inch pieces), thawed and drained
1 package sugar-free strawberry jello
1/2 cup splenda
2 cups miniature marshmallows
1 yellow cake mix
1 can clear diet soda
Whipped topping, optional
Preheat oven to 350ºF. Place rhubarb in greased 9 x 13 pan. Sprinkle evenly with jello, splenda and marshmallows. In separate bowl, combine cake mix and diet soda. Mix until batter is smooth, typically following package directions. Pour batter on top of marshmallows.
Bake 50 to 55 minutes until cake layer is done. (Use a toothpick to test, but beware the the rhubarb layer is gooey.) I prefer this served warm with a dab of whipped topping.