Bake this delicious potato casserole as a main dish or side dish. Ham and cheddar cheese make it hearty enough to serve as a one-pot meal, or use a bit less ham and make it a side dish. It's an excellent casserole to take along to a potluck dinner. Replace the green onions with 1 cup of chopped yellow onions or omit the onions altogether. Feel free to add some steamed peas and carrots or mixed vegetables to the potato mixture for more color and nutrients. The best choice for potatoes is a medium starch potato like the kennebec or yukon gold. The starch content makes for a creamy sauce while they tend to hold their shape better than russets. Scale the recipe up for a potluck or make two casseroles and freeze one. See the freezing and reheating instructions below the recipe.