Cut the chicken thighs in bite sized pieces. Saute the chicken and onion in the olive oil until cooked thoroughly. Reduce the heat and stir in the green chiles and black olives. Add the garlic power, onion powder and black pepper. Stir well. Add the taco seasoning and water. Stir well. Let the mixture come to a boil, then reduce the heat and let simmer.
In a 9 x 13 casserole dish, pour a small amount of enchilada sauce on the bottom and spread it around. In a small skillet, heat the corn tortillas until pliable. Do not overcook them. Place 6 corn tortillas on the bottom of the casserole dish, spread the refried beans over the tortillas, spread the chicken mixture, cover with cheese, then a drizzle of enchilada sauce. Repeat until you end with tortillas on the top. Pour the rest of the enchilada sauce on top of the tortillas and sprinkle with cheese. Bake in a 350 degree oven for about 30 minutes or until all the cheese on top is melted.
When you remove it from the oven, let it set for about 20 minutes before you cut it. Serve it with a dollop of sour cream and a sprinkle of green onions (optional).