Place chicken thighs (can be frozen) into a crock pot/slow cooker, and pour the 14 oz can of diced tomatoes and green chilies over the top--cook on low 6-8 hours.
Preheat oven to 350ºF.
Spray a 9 x 13" pan with non-stick spray.
In a large bowl, use a hand mixer to mix cream cheese until whipped and soft.
Add sour cream to cream cheese, and mix until smooth.
Using a slotted spoon or strainer, scoop out whole chicken thighs, tomatoes, and green chilies--leaving behind as much juice as possible in the crock pot/slow cooker, and place it into your sour cream/cream cheese mixture.
Mix until chicken is shredded and it is all well blended.
Place 1/2 cup green enchilada sauce in bottom of 9 x 13" pan, and spread around.
Place 6 corn tortillas over bottom of the pan overlapping slightly.
Spread about 1/3 of your chicken mixture on top of the tortillas.
Pour 1/2 cup-2/3 cup of green enchilada sauce on top of chicken mixture.
Sprinkle about 1 cup of shredded cheddar cheese on top of enchilada sauce.
Place 6 more corn tortillas, and repeat steps 10-12 with second 1/3 of chicken mixture.
Place 6 more corn tortillas, and repeat steps 10-12 with last 1/3 of chicken mixture.
Place 6 more corn tortillas on top, pour remaining green enchilada sauce over tortillas, and spread so that all the tortillas are covered.
Sprinkle any remaining cheese over top.
Bake for about 60 minutes or until bubbling and slightly brown on top.
Let cool for 10-20 minutes before serving, if you can, to allow layers to set.
Serve with additional sour cream, guacamole, or other toppings or sides.