High-heat the grill.
Mix chicken spice ingredients in a small basin. Crush spices with your fingers for a finer combination. Reserve.
Olive oil chicken breasts generously. Apply the spice blend and oil to both sides of the chicken breast. Reserve.
Medium-heat butter in a pot. Avoid burning prosciutto in butter for 2-3 minutes over medium-high heat.
Cook the shallots and mushrooms until soft. Sauté for 30 seconds after adding garlic.
Simmer Marsala wine for 30 seconds before adding freshly ground pepper. Simmer for 5 more minutes over medium-high heat. Reserve.
Mix cornstarch and chicken stock in a small basin. Simmer the stock for five minutes in the pot.
Simmer for five minutes after adding stock. Cover the pan until needed.
Grill the chicken for 6-8 minutes per side until done. Turn the chicken 1/4 turn on each side to form crisscross grill markings. Plate each chicken breast. Serve chicken with 1/4 cup Marsala wine sauce. Enjoy!