This is a rich and delicious macaroni & cheese from Bon Appétit Magazine (May 2009). You can use any combination of good melting cheeses such as Gruyere, Emmentaler, Fontina, or cheddar. It works with kale, chard, or spinach. If you omit the greens, this also makes a great traditional mac & cheese. If you want a creamier macaroni & cheese, just add a little more milk until you get the desired consistency.