CRUNCH:

1 c. melted butter
1 c. flour
1 c. brown sugar
3/4 c. oatmeal
1 tsp. cinnamon

Put half of this mixture on bottom of 9x13 inch pan. Press in.

FILLING:

4 c. cut-up rhubarb (no bigger than 1/2 inch)
2 tbsp. cornstarch
1 c. water
1 c. sugar
1 tsp. vanilla

Heat until mixture turns clear. Pour over bottom crunch and pat on remaining mixture. Bake at 350 degrees for 1 hour. When using a pan larger than 9x13 inches, triple the recipe.