Place chicken on cutting board. Holding sharp knife horizontal to board, cut a 3-in.-deep pocket lengthwise in each breast. Stuff each pocket with one slice of mozzarella cheese and two basil leaves. Sprinkle chicken with salt and pepper; wrap two slices prosciutto around each chicken breast. Heat oil in a large ovenproof skillet. Add chicken and cook over medium-high heat until browned, about 3 minutes each side. Transfer chicken in skillet to oven; bake at 350 degrees for 12-15 minutes or until juices run clear.