Butterfly breasts, and sprinkle with pepper. Place 5 leaves on each breast, the top with 2 slices of prosciutto, tucking ends under. Drizzle top with a bit of oil.
Heat remaining oil in skillet and cook chicken on both sides. Remove and set aside.
To skillet add butter, garlic and remaining sage into pan, stirring and deglazing pan until garlic is fragrant and a sauce is created.