Gather all of your ingredients. Preheat your oven to (350°F) = (176°C).
Crush the Frosted Flakes in a bag. Note: You are welcome to use another cereal or favorite cracker, if desired, in place of the Frosted Flakes. The Frosted Flakes give the casserole a sweet flavored topping that is delicious and pairs well with the other ingredients.
Combine all of the ingredients in a large bowl, and sprinkle with salt and pepper. (Except for the Frosted Flakes and butter, set them aside).
Stir the ingredients until smooth.
Grease a 9 by 13-inch pan with cooking spray and scoop the mixture into the pan or casserole dish.
Bake at (350°F) = (176°C) degrees covered with aluminum foil for 1 hour or until bubbly.
Combine the melted butter and crushed Frosted Flakes, you will sprinkle these on the casserole before baking or add them to the baked casserole, for the last 15 minutes of baking.