Season the chicken breasts with garlic powder, Italian seasoning, and salt and pepper to taste. Place 5 slices of pepperoni on each breast and divide the cheese among the breasts. Roll up the breasts and seal with toothpicks.
Chop the remaining pepperoni and place in a medium skillet. Heat until they have released most of their fat. Remove the pepperoni and set aside. Place the chicken roll ups in the skillet and fry in rendered fat for about 5 minutes per side, or until golden brown. Place the chicken in a baking dish. Combine the pizza sauce and the fried pepperoni and pour over chicken.
Bake for 30 to 40 minutes, or until the chicken is cooked through.