Blackberry Pie

1 quart blackberries, washed and drained
¾ cup water
1 cup sugar
3 tablespoons cornstarch
1 tablespoon butter
1/8 teaspoon salt
Baked 9" pie shell

Mash 1 cup of berries. Put them in a saucepan, add ¾ cup water and cook four minutes. Mix sugar and cornstarch and add to water and berries. Cook until thick and clear, stirring frequently. Add lemon juice, butter and salt. Stir to mix. Let mixture cool. Arrange whole berries in pie shell. Pour cooled mixture over whole berries. Refrigerate until chilled. Top with whipped cream or vanilla ice cream, if desired.