Here's how I make my scalloped potatoes. It's pretty easy, once you get the hang of the white sauce, plus it tastes way better than those boxed mixes! LOL This is from memory; I think I've lost my original recipe.
4 medium potatoes, peeled and thinly sliced
1/4 cup margarine or butter
1/4 cup all-purpose flour
2 cups milk
1/2 cup shredded cheese (American gives a smooth sauce, cheddar is gooey)
Dash salt and pepper, to taste
Peel and slice potatoes. Melt margarine in medium saucepan. Stir in flour till smooth. Add milk all at once. Cook, stirring constantly, till mixture comes to a boil, then cook one more minute. Remove from heat and add cheese; stir till melted.
In a 9x13-inch baking dish, layer potatoes, followed by a layer of cheese sauce. Repeat layers. Cover and bake at 350 for 45 minutes. Uncover and bake for 30 more minutes until potatoes are tender golden brown on top.
For a one-dish meal, add a layer of ham after each layer of potatoes.