Spread a light amount of mayo on each side of your bread. 

Slice fontina cheese and tomato (if using). 

Place 2-3 slices of fontina on one side of bread.  Top with prosciutto slices, tomato, and torn basil.  Top with 2-3 more slices of cheese.  Put other piece of bread on top. 

In a small skillet, melt a small pat of butter.  Once it is melted, add your sandwich to the pan and halfway cover the pan.  Toast one side and then flip to toast the other side (add a little more butter if needed). 

Once your sandwich is toasted and the cheese is melted, remove the sandwich from the pan.  

Take a clove of garlic and cut it in half.  Rub the toasted bread with the cut garlic.  

Cut in half and enjoy!