In a large mixing bowl, mash enough berries to equal 3 cups. In a saucepan, combine the sugar and cornstarch. Stir in the mashed berries and water; mix well. Bring to a boil over medium heat, stirring constantly. Cook and stir for 2 minutes. Remove from the heat; add food coloring if desired. Pour int a large bowl. Chill for 20 minutes, stirring occasionally, until mixture is just slightly warm. Fold in the remaining berries. Pile into pie shell. Chill for 2-3 hours. In a small mixing bowl, whip cream until soft peaks form. Sprinkle pudding mix over cream and whip until stiff. Pipe around edge of pie or dollop on individual slices.