1 baked (9-inch) pie shell
4 c. fresh or frozen blueberries
1 c. sugar
3 tbsp. cornstarch
1/4 tsp. salt
1/4 c. water
1 tbsp. butter

Line cooled pie shell with 2 cups blueberries. To make sauce: cook remaining berries with sugar, cornstarch, salt, and water over medium heat until thickened, stirring constantly.

Remove from heat, add butter, and cool. Pour over berries in shell. Chill until serving time. If desired, serve with whipped topping.