Take 1 chicken breast and butterfly it open so you have 1 large piece of chicken. You can pound out the high spots if you want, but it’s not necessary. Season the inside of the breast with salt and pepper. Layer in one slice of prosciutto, one slice of fontina cheese, and one sage leaf. Roll the chicken breast up and place on a piece of parchment paper on a baking tray, seam side down. Season the top with more salt and pepper, and place one more piece of fontina on top of the rolled up chicken breast. Bake in a 350 degree oven for about 10-12 minutes, or until internal temperature reaches 165 degrees.