Blend the mozzarella for 2 minutes to form a paste.
Spread the truffle paste on each slice of tramezzino.
Spread the mozzarella on top of the truffle paste.
Add Ibérico ham to one slice of bread. Place the remaining piece of bread on top to complete the sandwich.
Melt the butter in a non-stick frying pan over medium heat.
Once the butter has melted, place the sandwich in the pan and press down lightly for 30 seconds. Release and continue to cook for 2 minutes.
Spread remaining butter on the top of the sandwich and flip.
Continue to cook until all the cheese has melted.
Remove the sandwich from the pan. Cut into 4 equal pieces and enjoy.