5-6CupsPotatoescleaned, and thinly sliced. I peeled mine but you can also keep the peelings on if you wish.
2MediumOnionsDiced-you can use just 1 onion if you wish, but we like a lot of the cooked onions in this bake.
1/2Tsp. PepperYou can also add salt at this point if you wish. I feel the butter and cheese has enough salt; therefore, I do not find this dish needs salt.
3CupsShredded CheeseI used Colby/Jack-there are other good choices, use the kind you like.
3Cupsprecooked HamCut up into small bite sized pieces.
Spray oil for spraying pan and foil
Preheat oven to 400 F.
Prepare a 9 X 13 baking pan with spray oil, such as Pam.
Scrub and slice the potatoes. I like to peel mine, but peeling is optional. Slice thin and make the potato sizes close to the same size for even cooking.
Chop the onions.
In a saucepan over medium-high heat, melt the butter. Add the flour and whisk until incorporated.
Add the milk and cook 3-4 minutes continuing to whisk. Add the pepper and if you wish (salt) at this point. Turn off the heat.
Begin layering the ingredients. Add about 1/3 of the potatoes, top with the part of the onions , ham and cheese. Repeat the layering once more.
Add the sauce and finish adding the cheese to the top.
Cover with aluminum foil (spray with oil such as Pam to prevent the cheese from sticking).
Bake at 400F for 30 minutes. Reduce heat to 350F and bake until the potatoes are fork tender. Approximately 90 minutes. The casserole should be nice and bubbly. Allow to set for about 10 minutes before serving.
Short on time? No worries. The baking time can be reduced by boiling the sliced potatoes ahead of time about 10 minutes. The baking time can be cut in half, all that the casserole needs to do is get hot and the cheese melty.