Combine the chicken and enchilada sauce in a skillet over medium-high heat.
Stir, then add in the black beans and diced peppers.
Mix in the sour cream and corn tortilla pieces, continue to stir.
Once everything is evenly hot, top the casserole with cheese and optional cilantro.
Serve with avocado slices and enjoy or store in the refrigerator for later in the week!