Preheat oven to 350 degrees. In a skillet, melt 4 tablespoons of butter. When it starts to brown, add 3-4 cloves of minced garlic. Add sage leaves and cook for 1 minute, just to soften. (Do not burn the butter.) Wash and pat dry the chicken breasts. Make 5-6 diagonal cuts three quarters of the way through the chicken. Place chicken on a 9X13 baking sheet. Roll up prosciutto slices. Tuck prosciutto, slice of cheese and a sage leaf into each slit in the chicken. Spoon garlic butter over the chicken. Lightly season with salt and pepper. Sprinkle Mozzarella over each piece of chicken. Bake for 25 minutes, basting half way through the cooking process with the melted garlic butter. Optional, serve on a bed of warmed marinara sauce.