To prepare crust, combine cereal crumbs, margarine, and brown sugar in a mixing bowl. Press mixture firmly in a 9" pie pan. Chill one hour, or until firm. Or, bake in a 375 oven for 10 minutes or until edges are brown. Cool on rack before filling. Preheat oven to 350. To prepare filling, combine cream cheese, granulated sugar, eggs, one cup applesauce, and vanilla extract. Mix until smooth. Spread into crust. Bake for 40 minutes, or until center is set. Cool completely. Refrigerate three hours before serving.