Mix in saucepan:

2/3 c. sugar
2 tbsp. cornstarch
1 tsp. lemon juice
2 c. black raspberries, fresh or frozen
1/2 c. water

Cook over medium heat, stirring constantly, until mixture is thick. Remove from heat and cool. Pour filling in an 8-inch pastry lined pie pan. Dot 1 tablespoon butter on top of filling. Cover with top crust. Bake in 425°F oven for 35 to 40 minutes, or until crust is nicely browned.