Chop up onion and garlic. Place in a sauce pan over medium-low heat with olive oil and let tenderize while you prep. Stir occasionally.
Add tomatillos (husked and washed), chicken broth, cilantro, oregano, cumin and salt to a blender or food processor and blend until somewhat smooth. Set aside.
Cook your chicken with salt and pepper. You can boil it, cook it on the stove or if you're in a real rush use a rotisserie chicken but you won't need the entire chicken!
Once your chicken is starting to cook, your onions and garlic should be tender. Add the blender ingredients and let simmer for 7-10 minutes. (But don't wash that blender yet!)
Preheat oven to 350 degrees.
Once your chicken is cooked, let rest for 5 minutes and then chop.
Remove enchilada sauce from heat and return to the blender. Blend again, but don't seal the lid on because the steam from the heat can make the top blast off! So use a dish towel to gently hold the lid partially off, the dish towel should keep you from getting burned from the steam too!
In a large bowl, combine chopped chicken, green chiles (optional), sour cream, and 1 1/2 cup of cheese. Stir.
Pull out a 9X13 inch casserole dish (or you can use whatever you have on hand). I gave my pan a little spray of coconut oil for easy cleaning and I also poured about 1/3 of my enchilada sauce into the bottom of the pan to keep everything from sticking as well.
Assemble: Take your tortillas one by one and fill with a scoop of your chicken mixture. Roll and start again. Continue until the pan is filled. Pour enchilada sauce over tortillas and sprinkle with the remaining cheese. Use as much or as little cheese as desired.
Bake for 25-30 minutes or until it's heated through. I usually wait for bubbling in the enchilada sauce!