1/4 c. cornstarch
1/2 c. sugar
1/2 c. water
3 c. blueberries
1 (13 1/2 oz.) pkg. graham crackers
1 1/2 sticks butter, melted
2 (8 oz.) pkgs. cream cheese
1 1/2 c. sugar
2 tsp. vanilla
1 (9 oz.) pkg. frozen whipped topping

Mix cornstarch, sugar, water and blueberries and cook, stirring constantly until sauce bubbles and thickens. Cool. Combine cracker crumbs and butter. Press 1/2 of crumbs into 9 x 13 inch pan. Mash cream cheese until soft and gradually beat in sugar and vanilla. Fold in whipped topping. Spread 1/2 of this mixture over the crumbs. Next spread blueberry mixture followed by other half of cream cheese mixture and rest of graham cracker crumbs. Chill overnight.