Prepare stuffing according to package directions. Wash the chicken, pat dry and pound out to about a 1/2 inch thickness. Place a slice of cheese on each breast, followed by a scoop of prepared stuffing. Close each breast over the cheese and stuffing and hold with a toothpick. Place stuffed breasts in a lightly greased 9x13 inch baking dish.
Bake at 350 degrees F (175 degrees C) for 25 minutes, or until chicken juices run clear, then place a second slice of cheese over each stuffed chicken, and bake for 2 more minutes, or until cheese is bubbly.