Preheat oven to 350 degrees. In a very large bowl, stir together margarine, brown sugar and granulated sugar. Stir in eggs and vanilla. Stir in rolled oats and corn flakes. In a smaller bowl, stir together flour, baking soda and baking powder. Stir flour mixture into sugar mixture.Add 1 or 2 stir-ins. Drop dough from serving spoon, 0.5-cup measure or ice cream scoop onto ungreased cookie sheets. Leave plenty of room; cookies will spread. Bake about dozen minutes or until done. 4 to 5 dozen cookies.