Schmear a layer of mayo or butter on the bread slice's outside and put it in a pan. The heat will crisp up the bread and turn the cheese into a consistency like Parmesan crackers.
Gruyère cheese is creamy and delicate with a profound nuttiness. It's so fatty that it melts easily, which gives you a perfect grilled cheese with a great cheese pull.
It's rare to find a Gruyère aged for more than six months, so expect a mild flavor that can complement herbs, caramelized onions, or a meaty addition to your sandwich.
Brie is a soft cheese with a high moisture content, so adding it to your sandwich will make for a melty, gooey mess. Remove the rind from it first so it doesn't come out chewy.
Ripeness and flavor depend on aging. Brie can be punchier than expected to some palates, so you'll have to get creative in taming the flavors with other ingredients.
If you have enough time, it's better to grate your own cheese. Pre-grated cheese often has fillers that prevent it from clumping in the bag and doesn't melt as easily.
Cream cheese is deliciously moist and sharpens the contrast between the crunchy, crisp bread and the soft filling. You can mix it with other melting cheeses, too.
Its mild tang is a welcomed pairing for sharper cheeses or mild varieties. It can also be whipped up into a pimento grilled cheese by mixing it with cheddar, mayo, and seasoning.