In a small bowl, combine the ingredients for the chicken spice. To make a finer blend, crush the spices with your fingers. Place aside.
Apply olive oil generously to chicken breasts. Mix the spice blend with the oil, and rub it into the chicken breast on both sides. Place aside.
In a medium saucepan, melt butter on medium heat. Sauté prosciutto in butter for 2-3 minutes over medium-high heat, being careful not to burn it.
Then add the shallots and mushrooms, and cook until the vegetables are tender. Stir in the garlic and saute for another 30 seconds.
Pour in the Marsala wine and simmer for 30 seconds, then add the freshly ground pepper. Over medium-high heat, simmer for more 5 minutes. Put aside.
Mix corn starch with chicken stock in a small bowl. Add the stock to the saucepan and simmer for an additional five minutes.
Stir in the stock and simmer for another five minutes. Then remove the pan from the heat and cover it until you need it.
Grill the chicken pieces for about 6-8 minutes per side, or until they are cooked through. While cooking, turn the chicken one quarter turn on each side to make criss-cross grill marks.
Place each chicken breast on a plate. Add 1/4 cup of Marsala wine sauce to each serving of chicken and serve. Enjoy!