Yes, if you have too much fontina, you can freeze it, however, the texture may become somewhat crumbly on defrosting. The best way to use cheese that has been frozen is to melt it into cooked dishes or toasted sandwiches. Slice or grate the fontina into the desired portion sizes so you can remove only what you need from the freezer at any given time. Make sure to keep it in airtight freezer bags to prevent any exposure to air or moisture.