Baked pie shell, cooled (can use regular or graham cracker crust -- I prefer regular)
Mash enough berries to make 1 cup (you can also use a blender). In a saucepan, whisk together sugar and cornstarch. Gradually stir in water and crushed berries. Heat over medium heat, whisking constantly, until mixture thickens. Boil and stir one minute. Cool completely. If using cream cheese, spread along crust. Pour cooked berry mixture and remaining berries (left whole) over crust. Drizzle melted chocolate over the top, if using. Refrigerate at least 3 hours.