Spread one french bread slice with pesto. Set aside.
Butter the other slice of french bread. Place butter side down onto a heated skillet.
Add cheese onto bread. Place other slice of bread with pesto on top (pesto side down).
Press down the top of the sandwich with a heavy skillet until sandwich flattens like a panini. When bread is browned, pull off the skillet on top of the sandwich and carefully butter the slice of bread on the top and then flip sandwich over.
Can use skillet again on this side if desired. When brown, pull off heat and enjoy!