Mix 1st 5 ingredients together. Press 1/2 of mixture into 8.5 X 11 pan. Sprinkle 2.5 - 3 Cups of chopped (3/4 in. pcs.) Rhurarb - or other fruits of your choice over 1/2 of the mixture. Mix sugar, cornstarch, water & vanilla together and heat til sugar is dissolved. Cool sauce til thickened. Pour over rhubarb. Sprinkle remaining 1/2 of crumb mixture over top of sauce.
Bake at 350 degrees for 1 hour. Great served with vanilla or strawberry icecream. Enjoy!