Combine in bowl. Pour into bottom of 9x13 cake pan (glass preferred). On top put at least 3 cups of chopped rhubarb.
Then mix the sugar & hot water together and pour over rhubarb/cake batter mixture. Bake at 400 degrees for 35 minutes. (Now - this is the cake that makes a dirty oven! So put this pan on a cookie sheet when you bake it because it invariably runs over!) This is a quick cake to make and simple and easy, and very delicious. You may use apples instead of rhubarb, too - but cut down sugar a little if you like in recipe.