In large Dutch oven over medium heat, sauté onion in olive oil until translucent.
Add garlic and stir into onions. Add salt, pepper, chili powder, cumin, and ranch dip mix. Crush dried oregano between your hands to release oils, then add to Dutch oven and stir and cook until fragrant, about a minute.
Add tomatoes and green chilies with juice, Knorr chicken bouillon cubes, water, and chicken broth. Cook and stir to combine.
If using raw chicken, add it to the broth mixture now. Heat to boiling with lid partially covering the pot to allow steam to escape. Once it starts to boil, reduce heat and simmer for about 25 minutes or until chicken tests done at 165 degrees with a meat thermometer inserted in thickest part of chicken breast. Remove chicken from broth to plate to cool slightly before shredding. Set aside.
If using already cooked, shredded chicken, add it when adding the beans.
Add cubes of cream cheese to broth and whisk to combine until melted and smooth. Add heavy cream and heat on medium heat until bubbly. Then turn heat down to simmer.
Add shredded chicken, beans, and corn, if using.
Simmer until heated through, about 20 minutes.
Squeeze in lime juice to taste. Serve with Monterrey jack cheese, avocado, and tortilla chips, if desired.