Swiss cuisine is based around dairy foods and this recipe makes excellent use of Gruyere cheese. This casserole is easy to prepare, especially if you purchase diced ham from your supermarket, it is great for brunch or a light dinner. Gruyère is a type of Swiss cheese. Its sweet nuttiness enhances this dish, though you can substitute Edam, Gouda, or even cheddar cheese. Note that it needs to be chilled 8 hours or overnight.