Lay 1 slice of prosciutto on each chicken cutlet. Squeeze the frozen spinach to remove the excess water. Season the spinach with salt and pepper and a little olive oil. Arrange an even, thin layer of spinach on top of the prosciutto slices. Sprinkle the Parmesan cheese evenly over each. Beginning at the short, tapered end, roll up each chicken. Secure with a toothpick.