To cook cheesy scalloped potatoes, make a cheese sauce with 3 tablespoons of melted butter, 2 tablespoons of flour, 1 1/2 cups of cold milk, 1 cup of grated cheddar cheese, salt and pepper, and pour it over 4 cups of sliced potatoes. Bake uncovered at 350 degrees Fahrenheit.
Whisk together butter and flour over low heat. Allow the butter and flour blend to rest for a minute before adding the cold milk, 1 teaspoon of salt and a dash of cayenne pepper. Heat this mixture over low heat until it boils, add the cheese, and whisk together until smooth. Place half of the sliced potatoes into a lightly greased casserole dish, cover with half of the cheese sauce, and repeat with a second layer of potatoes and cheese sauce. Sprinkle 1/2 cup of grated cheddar cheese and a pinch of paprika on the top, and bake for about one hour at 350 degrees Fahrenheit.
To make cheesy scalloped potatoes in a microwave oven, gradually mix 3/4 cup of milk and one can of cream of chicken soup in a 2-quart casserole dish. Add 4 cups of thinly sliced potatoes, 1 cup of grated cheddar cheese, 1/4 cup of diced onion, 1/2 teaspoon of salt and a dash of pepper. Cover this mixture tightly and microwave on high for 10 minutes, stir, cover, and microwave again on high for another 10 to 15 minutes. Right before serving, sprinkle with Parmesan cheese, if desired.