3/4 Rolled Oats
1 Brown Sugar
Mix flour, rolled oats, brown sugar, margarine and cinnamon until crumbly: Press half of this mixture into a 9 greased pan.
Cover with chopped rhubarb.
Combine sugar, cornstarch, and water.
Cook until thick and clear in a small saucepan.
Remove from heat and add vanilla.
Pour over rhubarb. Top with remaining crumbs.
Bake at 350°F for 1 hour.