Ingredients:

4 cups fresh blueberries
3/4 cup water
2 tablespoons cornstarch
1 tablespoon freshly squeezed lemon juice
1 tablespoon butter
3/4 cup sugar
1 pre-made crust, baked

Instructions:

Bring one cup of blueberries with all but 2 tablespoons of water to a boil
Cook about 4 minutes, until blueberries begin to pop
With remaining 2 tablespoons of water, dissolve the cornstarch with lemon juice
Add to berries
Cook, stirring until mixture is thick and glossy
Remove from heat
Add remaining fresh berries, mix  and pour into baked crust
Refrigerate for at least one hour