Preheat oven to 350. Prepare a 9"x13" pan with cooking spray; set aside. To prepare crust, combine flour, walnuts, and brown sugar in a mixing bowl. Add margarine and mix until crumbly. Lightly pat into prepared pan. Bake for 18 minutes or until golden brown. Cool completely. To prepare filling, combine cream cheese, powdered sugar, and vanilla extract until smooth. Fold in whipped topping. Carefully spread over crust. Spread top evenly with cherry pie filling. Cover and refrigerate several hours before serving.