Place the chicken at the bottom of the crock pot, sprinkle with the taco seasonings and then pour the enchilada sauce on top.
Cover the pot and cook on low for 1.5 to 2 hours, it depends how thick the chicken breasts are, just monitor it until it is completely cooked (165 degrees). I suggest using a thermometer that you can keep in the closed crock pot.
Once the chicken is fully cooked, shred it using two forks, a hand mixer or meat masher. Add it back to the crock pot.
Pour in the cheese and the sour cream, mix to combine.
Cut the corn tortillas into 8 equal sized triangles. Add to the crock pot and carefully mix to combine.
Close the crock pot for 5-10 minutes to allow the cheese to melt.