Pour the black beans into a fine-mesh strainer. Rinse under cool running water for 20 to 30 seconds, then drain well.
Add the black beans to the slow cooker. Layer the drained corn and undrained tomatoes with green chiles over the beans.
Coat both sides of the chicken breasts with chili powder, cumin, garlic powder, onion powder, and ranch seasoning.
Place the seasoned chicken breasts in a single layer over the beans, corn, and tomatoes.
Place the whole 8-ounce block of cream cheese on top of the chicken. Do not stir it into the chili yet.
Cover and cook on LOW for 6 to 7 hours or HIGH for 3 to 4 hours. Check the thickest part of the chicken with a food thermometer. It must reach at least 165°F / 74°C.
Transfer the cooked chicken to a clean plate. Pull it apart into bite-size pieces with two forks, then return it to the slow cooker.
Break apart the softened cream cheese and stir it through the chili for about 2 to 3 minutes, or until the sauce looks smooth and creamy.
Set the slow cooker to WARM and leave the lid slightly open. Let the chili rest for 10 to 15 minutes.
Spoon the chili into bowls and finish with cheese, avocado, green onions, tortilla chips, cilantro, sour cream, jalapeños, lime, or hot sauce.