Rhubarb Cake 5 cups rhubarb, 1 3oz pk strawberry jello, 1 cup sugar, mini marshmallows, 1 pkg yellow cake mix, Mix up yellow cake according to box directions. Layer rhubarb, jello, sugar and then marshmallows. Pour cake mix over the top. Grease a 13x9 cake pan. Bake at 350 degrees for 50-60 min. Flip out let cool and top with cool-whip or ice cream. (I was not able to flip out this one) I just spread the cool whip over the top and served.