1 cup all-purpose flour
1 cup old-fashioned oats
1 cup packed brown sugar
1 teaspoon ground cinnamon
1/2 cup cold butter, cubed
4 cups diced fresh rhubarb or frozen rhubarb
1-1/3 cups sugar
2 teaspoons cornstarch
1 cup cold water
1 teaspoon vanilla extract
Vanilla ice cream, optional
Directions:
In a large bowl, combine the first four ingredients. Cut in butter until mixture resembles coarse crumbs. Press half of the mixture into a greased 8-in. square baking dish. Set remaining crumb mixture aside for topping. Sprinkle rhubarb over crust; set aside.
In a small saucepan, combine the sugar and cornstarch; gradually whisk in water until smooth. Bring to a boil; cook and stir for 2 minutes or until thickened.
Remove from the heat, whisk in vanilla. Pour over rhubarb. Sprinkle with reserved crumb mixture.
Bake, uncovered, at 350° for 1 hour or until bubbly and lightly browned. Serve warm with ice cream if desired.