SPREAD half of the butter on one side of the first slice of bread; place buttered side down onto a nonstick skillet over medium heat.
SPREAD half of the pesto on the top of the bread in the skillet.
PLACE provolone cheese, tomato (optional) and American cheese onto the pesto side of the bread.
SPREAD remaining pesto on one side of the second slice of bread; place pesto side down onto the sandwich. Spread remaining butter on the top side of the sandwich.
GENTLY fry the sandwich, flipping once until both sides are golden brown and cheese has melted, about 5 minutes per side.
SERVE with a bowl of your favorite tomato soup topped with parmesan.
