Boil chicken until cooked through. Shred using a stand-up or hand mixer.
Slice corn tortillas into quarters each using a large knife or pizza cutter. They will be in triangles. You can skip this step but it makes cutting into the casserole easier.
In a large bowl combine your chicken with the taco seasoning and Rotel and mix well. Set aside.
Spray the inside of your crock pot casserole dish with non-stick cooking spray.
Pour a little enchilada sauce on the bottom of your pan, then start your layering.
Cover the bottom of the pan with tortillas (you don’t have to cover every single gap). Top the tortillas with the shredded chicken mixture. Pour enchilada sauce over the chicken.
Top with shredded cheese.
Continue layering tortillas, chicken, sauce, and cheese.
You should have enough chicken for about 3 full layers. Finish the casserole off with a layer of tortillas, the rest of the enchilada sauce and cheese.
Place the lid on the casserole and cook on low for 2-3 hours.
Cut and serve with sour cream, tomatoes, cilantro and onions.