For the chicken
01 -
4 boneless skinless chicken breasts, about 1 3/4 lb (800 g) total
02 -
1 teaspoon kosher salt
03 -
1/2 teaspoon black pepper
04 -
2 tablespoons olive oil
For the sauce and topping
05 -
4 tablespoons (56 g) unsalted butter
06 -
1/2 medium yellow onion, finely diced
07 -
4 garlic cloves, minced
08 -
8 oz (225 g) cremini or white mushrooms, sliced
09 -
3 oz (85 g) prosciutto, cut into thin strips
10 -
1/3 cup (80 ml) fresh lemon juice
11 -
4 slices fontina cheese, about 4 oz (115 g)
12 -
1/4 cup fresh basil leaves, thinly sliced