1
Cut each breast across the center into two pieces. Place 4 pieces of chicken breast on a large piece of wax paper, and cover with another piece of wax paper. Pound the chicken pieces with a mallet until each one is approximately 1/8 inch thick. Season with ground pepper and set aside.
2
Heat butter over medium heat in a large saute pan. When the butter is foaming, add the sage leaves and cook them on each side for 1 minute. Remove immediately, and place 1 tbsp on each of the chicken pieces. Then, wrap each piece completely in a single layer of prosciutto (ham).
3
Dip the wrapped chicken pieces, one at a time in the beaten eggs, coating them well. Make sure the butter in the pan is foaming golden, not browned. Then place the chicken pieces in the pan. Cook the chicken breasts about 2 minutes on each side, or until they're just past pink on the inside, golden on the outside. Remove.
4
Place chicken pieces on a flat baking sheet, and cover each piece with a slice of Fontina. Place under a preheated broiler until the cheese just melts, about 1 minute. Divide chicken among 2 plates and serve immediately.