Fontina Cheese + Mushroom Sandwiches

For the first time in my life, I had Fontina Cheese the other day. I was AMAZED at it's taste, creaminess and texture. It's... how do I explain? Perfection perhaps? :)

Ingredients:
Fontina Cheese - Italian version
Sliced Mushrooms
Diced Onion
Sourdough bread- toasted
Butter for cooking

Take the sliced mushrooms and diced onions and saute' in warm pan with butter for a few minutes. Add Fontina cheese to sourdough bread and lightly toast. Add mushroom + onion mix to the top. You can put back in the pan if you need it more toasty. Devour. Amazing or what???