1 c. flour
3/4 c. uncooked oats
1 c. brown sugar
1/2 c. melted butter
1 tsp. cinnamon
4 c. diced rhubarb
1 c. sugar
2 tbsp. cornstarch (or 4 tbsp. flour)
1 c. water
1 tsp. vanilla

Mix together flour, rolled oats, brown sugar, melted butter, and cinnamon. Put half of this crumbly mixture in a greased 9-inch cake pan. Cover with rhubarb.

Combine sugar, cornstarch, water, and vanilla in small saucepan. Cook, stirring until thick and clear. Pour mixture over rhubarb. Top with remaining crumbs. Bake in 350 degree oven for 1 hour. Cut in squares. Serve warm with whipped cream.