Preheat the oven to 350 degrees F. Combine all of the ingredients except the graham crackers and optional ingredients in a bowl, and mix thoroughly. Place the mixture in a deep-dish pie pan sprayed lightly with nonstick spray, and bake in the oven for 45 minutes. (It will remain a little soft, like pie filling.) Refrigerate until completely chilled and firm, at least 2 hours. Top evenly with crushed graham crackers. Add whipped topping and cinnamon, if you like. Serve and enjoy!