Gather all your ingredients on the counter.
Spread 1 tablespoon of pesto evenly on one side of each slice of bread.
Place one slice of cheese on top of the pesto on each slice of bread.
Carefully form a sandwich with the pesto and cheese sides facing each other.
Spread 1 tablespoon of butter on the outer side of the sandwich.
Heat a skillet over medium heat and add the sandwich, buttered side down.
Cook for 3-4 minutes until the bottom is golden brown.
Add remaining butter to the top side, flip the sandwich, and cook another 3-4 minutes until golden and cheese is melted.
Remove from skillet, slice in half, and serve warm.
