Cook pasta shells in well salted, boiling water until al dente (still have a little bite to them) If you cook them too long, they will be difficult to stuff, plus they will have additional cooking time, once they are stuffed. Drain the pasta and set aside while you make the filling.
Cook, drain and dice enough chicken breast to make 4 cups. I always have homemade chicken stock and pre-cooked diced chicken bagged in my freezer. You could use canned chicken broth if you prefer.
To make the filling, mix diced chicken, drained black beans, green onions, diced peppers, and cumin in a large mixing bowl. Thoroughly incorporate all the ingredients.
In a separate bowl, mix the cream cheese, chicken stock and undrained tomatoes with chiles. When thoroughly combined, pour it over the chicken mixture and mix well. (If you have trouble incorporating the cream cheese and tomatoes, you can heat it slightly in the microwave.)
Spread 3/4 c. picante sauce in the bottom of a large baking pan. (I used 13x