9-inch pie shell, baked
4 cups blueberries, divided
1 cup sugar
1/2 c water
1/4 c cold water
5 tbsp flour
Pinch salt
Cool Whip

Boil 1 C. blueberries with 1 C. sugar, 1/2 cup water. Blend together water, flour and salt to make a smooth paste. Add to the blueberries and stir until thick. Remove from stove, cool, add 3 C. blueberries, put in baked pie shell. Cover with Cool Whip. Chill and serve.