1. Butter bread slices on 1 side. Turn them over.
2. Lay cheese slices on 1 bread slice. Top with the other bread slice, buttered side up. (The buttered sides face out so that they'll turn crisp and golden when they touch the hot pan.)
3. Heat a medium frying pan over medium heat. Flick a drop of water into the pan; if it sizzles and evaporates, the pan is hot enough.
4. Put sandwich, buttered side down, in pan with both hands. Let it cook 3 to 4 minutes, or until golden and crunchy underneath. Using a spatula (or one in each hand, if the bread is large), turn the sandwich over. Let it cook another 3 to 4 minutes, or until golden and crunchy on the second side.
*Choose a cheese that melts well. Some classics for grilled cheese: cheddar, jack and pepper jack, Colby, gruyère, Swiss, fontina, provolone. Brie works well too.