Dethaw chicken breasts if frozen. Preheat oven to 350 F and lightly spray a 13x9 pan with cooking spray or lightly coat with shortening. Place a single breast into a ziplock, do not close. Continuously beat with mallet or rolling pin evenly until chicken breast is about 1/2 inch thick. Do this with every chicken breast.
Melt butter, coat both sides of chicken. Shred 1 3/4 cheese and mix with the tomatoes and chilis, 1/2 pkg of taco seasoning,1/4 C onion.
Put 1/4 cup of mixture in each breast. Do not overfill. Rolling is easiest if mixture is compact, tuck sides while roling away from you. Place in pan, edges on bottom.
Bring Enchilada sauce to a boil, stirring in the chilli powder, garlic, and remaining onion. Pour hot sauce over the breasts. Top with remaining cheese, and olives. Cover with tin foil.