Preheat oven to 350°. Combine crushed cereal and melted butter. Using the bottom of a glass, press cereal mixture onto bottom and up the sides of a greased 9-in. deep-dish pie plate. Bake until set, 10-12 minutes. Cool completely on a wire rack., Combine berries, 1/2 cup sugar, lemon juice and zest; let stand 10 minutes. Meanwhile, sprinkle gelatin over cold water; let stand 5 minutes. Transfer berry mixture to a food processor or blender; pulse until smooth. Press through a fine-mesh strainer to remove seeds. Microwave gelatin on high until melted, about 10 seconds; stir into berry mixture., Beat cream cheese and remaining sugar until smooth. Gradually beat in cream and berry mixture. Transfer filling to crust. Refrigerate, covered, until set, about 2 hours. If desired, top with sweetened whipped cream and additional berries.,