Put the chicken breasts and the enchilada sauce in your slow cooker. Cook on HIGH for 2 hours or LOW for 4 hours.
Shred the chicken right in the slow cooker, cut the tortillas into strips and then into squares and add to chicken and sauce. Stir to combine.
Add 1/2 cup of cheese and half the black beans into the sauce and chicken mixture. Stir again. Flatten the mixture. Add the rest of the cheese and the beans on top.
Cook on low for another 30 to 40 minutes until the cheese is completely melted. Serve immediately and top with sour cream and chopped scallions. Enjoy!