Lay each chicken breast half between two sheets of plastic wrap. Using a meat hammer, pound each half until it is uniformly ~1/4" thick, being careful to avoid making holes.
Remove the top sheet of plastic wrap.
Evenly season the top side of each breast half with a small pinch of salt and several grinds of black pepper.
Lay 2 prosciutto slices and 1 slice of provolone cheese on each chicken breast half.
Beginning with the small end, tightly roll up chicken breast half around the prosciutto and provolone (if the meat and cheese begin to squeeze out the other end, fold it back inward toward the center of the roll). Tightly wrap each breast half in the bottom piece of plastic wrap. Store in the refrigerator up to one day.
Remove the breast halves from the plastic wrap: if the rolls do not hold their form, secure the loose ends of each half with a couple of toothpicks (avoid colored toothpicks: the dye will come off during baking!).
Set up an assembly line to prepare the coating for the chicken rollatini: mix 1/2 tsp. of salt and 1/8 tsp. of freshly ground black pepper with the flour in a shallow dish or pie tin. Beat the egg and mix with the milk. Pour into a shallow dish and set next to the dish with the flour. In a third shallow dish, mix the panko breadcrumbs, Romano cheese, Herbs de Provence, and several grinds of black pepper; set next to the egg mixture. Coat each chicken breast half with the flour mixture, shaking to remove excess. Dip each rollatini into the egg mixture, coating evenly, and allowing the excess to drip off. Gently roll each rollatini in the breadcrumb mixture and set aside.
Heat your oven to 400 degrees. Meanwhile, lay a sheet of aluminum foil in the bottom of a baking sheet and set a baking rack inside. Spray the baking rack lightly with cooking spray; set the rollatini on the rack, seam side down.
Bake the rollatini for 30 minutes, or until an instant-read thermometer inserted into the thickest part of the rollatini reads 165 degrees F.
Remove the chicken rollatini to a cutting board and allow to rest for at least 10 minutes.
Slice the rollatini crosswise into pinwheels and serve. Enjoy!