Dice the onion and bell peppers and set aside. Heat a soup pot to medium heat and then add the butter to the pan. Once the butter is melted, add the diced onion and let the onions saute until they are tender and soft. Add the bell peppers to the onions and cook for a couple more minutes while you cut the chicken. Trim off any excess fat from the chicken breasts and cut into one inch pieces. Add the chicken pieces to the soup pot and cook until they are tender and cooked most of the way through. Add the cream cheese, chicken broth, frozen corn and seasonings to the pot and bring the mixture to a simmer. Simmer for 2-3 minutes to help melt the cream cheese and then add the white beans, evaporated milk and diced tomatoes. Continue to simmer on low heat until ready to serve, and the cream cheese is completely melted. Serve with tortilla chips and diced avocados as a garnish.