On a work surface, arrange four to six 18-inch pieces of twine each 3 to 4 inches apart and perpendicular to the edge of the work surface. Lay 3 of the prosciutto slices vertically, side by side, over the twine. Place the turkey breast, skin side down, on the prosciutto and bring up the ends of the prosciutto around the turkey breast. Place the remaining 3 prosciutto slices over the turkey breast to enclose the rest of the exposed meat. Tie the roast securely with the pieces of twine. Rub the breast with the olive oil.