Heat butter in cooker, add onion, carrot, celery, and cook over medium-high heat (sauté) until onion softens.
Add chicken broth, water, bay leaves, chili powder (optional), and chicken. Add tomatoes and green chilies (and/or hatch chilies).
Cook on High Pressure for 7 minutes (breasts).
Allow Natural Release for 4 minutes, then quick release.
Remove chicken to cutting board and shred/chop into bite-sized pieces. Return to soup, along with 1 cup of frozen corn. May try adding drained black beans. Cook until corn is tender.
Serve in bowls, topped with chopped cilantro, diced avocado, crushed tortilla chips, and Mexican cheese. May add a dash of lime juice.