Remove 1 cup berries and mash them. Combine sugar and cornstarch in a medium saucepan. Gradually stir in water and mashed berries, and cook over medium heat, stirring constantly, until mixture boils and thickens. Boil for about 1 minute, stirring all the time, then remove from heat and let cool.
Spread cream cheese over bottom of pie shell. Place remaining berries over cream cheese. Pour cooked berry mixture over fresh berries and chill in refrigerator until firm (about 2 hours).