Spread softened butter evenly on one side of each bread slice using a knife or spatula.
Place one bread slice, buttered side down, on the preheated skillet over medium heat.
Layer the provolone slices on top of the bread in the skillet, covering the surface evenly.
Top with the second bread slice, buttered side up, pressing gently to secure.
Cook for about 3-4 minutes, until the bottom is golden brown and crispy, then carefully flip the sandwich with a spatula. Continue to cook for another 3-4 minutes until the other side is golden brown and the cheese has melted, with visible bubbling.
Remove from the skillet once both sides are golden and the cheese is fully melted. Let it rest for 1 minute, then cut in half to reveal the melted provolone and crispy crust.