Preheat oven to 350°. Coat a baking sheet with nonstick cooking spray. In a large bowl, combine corn flakes, butter, sugar, and cinnamon. Mix well and spread on the baking sheet. Bake for 5 minutes or until lightly browned and crisp. It may help to stir the cornflake mixture around or turn it once while baking. Remove from oven and cool. In a 9 x 13 inch casserole dish, spread half the cornflake mixture evenly across the bottom. Cut the ice cream into slices about 1 inch wide. Lay the slices in the pan to cover the entire pan. As the ice cream will soften a bit in the process, use a knife or spatula to smooth the pieces together. Cover the ice cream with the remaining corn flakes mixture and pat it down. Cover the pan and freeze 2-3 hours until firm.