Heat a pan over medium heat, and add your olive oil.When the pan is warm, add in the spinach and garlic. Using tongs, toss the spinach and garlic regularly, until the spinach wilts, about 2-3 minutes. Add a pinch of salt and pepper, and set aside.Top one slice of bread with the cheese, and then top that with your sauteed spinach. Smear the top piece of bread with ½ tablespoon butter, and place on the sandwich, butter side up. Wipe your skillet clean with a paper towel, and return to medium heat.Add ½ tablespoon butter to the pan, and allow to melt. Place the sandwich in the pan, (buttered bread side up) and move around until the whole bottom piece of the sandwich is coated with the melted butter.Cook the sandwich for 3-4 minutes, making sure that the bread isn't burning. Flip over, and cook 3-4 minutes more, until the bread has browned, and the cheese is gooey.