Topping:

1 cup all- purpose flour
3/4 cups oats (quick or old-fashioned)
1 cup light brown sugar, firmly pcked
1/2 cup melted butter or margarine
1 teaspoon cinnamon 

Filling:

4 cups diced rhubarb
1 cup sugar
2 tablespoons cornstarch
1 cup water
1 teaspoon vanilla
Lightly sweetened whipped cream for topping, optional 

Mix together the topping ingredients until crumbly. Place diced rhubarb in a greased 9 inch square or round baking pan. In a small saucepan combine sugar, cornstarch, water and vanilla. Cook, stirring, until thickened and clear. Pour over rhubarb and top with remaining crumb topping. Bake at 350 degrees F. for about 50 to 60 minutes. Cut in squares and serve warm either plain or with whipped cream or ice cream. Rhubarb Crisp recipe makes about 8 servings.