Heat It Up: Preheat your skillet over medium heat. If you prefer, you can use a griddle for making multiple sandwiches at once.
Butter the Bread: Spread a thin layer of butter on one side of each slice of bread.
Spread the Pesto: On the unbuttered side of two slices, spread 2 tablespoons of pesto. Then, layer your cheese on top.
Assemble: Place the other slices of bread on top, buttered side out, to create a sandwich.
Grill It: Carefully place the sandwich in the preheated skillet, cooking until golden brown, about 3-4 minutes.
Flip and Cook: Flip the sandwich, pressing down gently with a spatula, and cook for another 3-4 minutes or until the cheese is melted and the bread is golden.
Garnish and Serve: Remove from the heat, garnish with fresh basil if desired, and cut in half. Dive in and enjoy!