Preheat oven to 350 degrees. Spray two 9x13 baking dishes with cooking spray.
In a skillet heat 1 teaspoon olive oil over medium heat. Add onions and cook until soft about 5 minutes, add garlic and stir another minute. Set aside.
In a large bowl add 1 can (the second can is for the topping) enchilada sauce and sour cream and whisk until smooth. Then add the chicken, green chilis, olives, onions, garlic, cheese and cilantro and mix until combined.
In a 9x13 baking dish add just enough enchilada sauce to cover the bottom about 3/4 cup. Fill each tortilla with about 3/4 cup of mixture, then fold up the tortilla, sides first then roll. Place in the dish seam side down and repeat.
Divide the remaining enchilada sauce and pour on top of the enchiladas, trying to cover all parts of the tortilla. Top enchiladas with shredded cheese. Place 1/2 olive on top of each enchilada. Loosely cover with foil
Bake for 30 minutes, remove foil and bake another 10 minutes. Allow to cool for 10 minutes and serve with your favorite garnish.