- Preheat oven to 350 degrees F. Prepare a jelly roll pan with cooking spray; set aside. 
- To prepare crust, combine graham cracker crumbs, oil, and 3 tablespoons sugar. Pat crumb mixture evenly on bottom of prepared pan. Bake for 10 minutes; cool. 
- In a saucepan, combine gelatin and milk. Let stand 2 minutes. Then, heat over medium heat, stirring constantly, until gelatin is dissolved. Cool to room temperature; set aside. 
- In a mixing bowl, combine cream cheese, lemon juice, lemon peel, vanilla, and remaining sugar. Add milk mixture.  
- Pour entire mixture over baked crust. 
- Refrigerate until set, about 4 hours. 
- Decorate with berries in a flag design.