Why am I calling these ultimate? First off, I love grilled cheese sandwiches. There are endless combinations, and honestly, since I love cheese.
Add sandwiches to skillet and cook until golden on bottom, about 4 minutes. Turn sandwiches over; transfer skillet to oven and bake until golden and cheese.
Butter; 4 slices country white sourdough bread, cut on deep diagonal into 1/3- inch-thick slices (each about 7x3 1/2 inches); 4 thin slices prosciutto; 8 large fresh.