Heat chicken broth over medium heat. Reduce heat to low while you prepare the rice.
Melt butter in a pan over medium heat. Stir in onions and cook until they are translucent. About 5 minutes.
Stir in rice just until it is coated in the butter. Do not brown. Pour in wine and cook until wine absorbs. Pour in one ladle of hot chicken broth. Stir consistently until liquid is absorbed. Repeat process, one ladle at a time, until all broth has been absorbed by the rice.
Remove from heat. Stir in mozzarella, fontina and parmesan cheese until they melt. Season to taste with salt and pepper. Let stand a few minutes. Serve.