3-4 ounces Fontina cheese (1 ounce per chicken breast)
For the Lemon Mushroom Sauce:
In a large non-stick skillet, heat 2 tablespoons of olive oil over medium high heat. Add the onions and saute for 2-3 minutes (until beginning to soften). Add the mushrooms and continue to cook until mushrooms have softened and begin to golden (5-10 minutes). Add the garlic and saute for another minute, until fragrant.
Add butter and lemon juice and stir well. Lastly, add chicken broth salt and pepper. Allow sauce to simmer and thicken a bit (5-10 minutes). Keep warm until ready to use. Add chopped basil to sauce just before serving.
For the Chicken:
Mix together the salt, oregano, and pepper and sprinkle mixture even over both sides of the chicken breasts. Grill over medium high heat until cooking through (8-10 minutes per side).
Place cooked chicken breasts on a sheet pan and add one slice of prosciutto to each chicken breast, then top with 1 ounce of fontina cheese. Broil until cheese in melted. Place chicken breasts on serving splatter and spoon the lemon mushroom sauce evenly over top of them.