Place chicken breast halves on a medium baking sheet (or boil them for 20 minutes). Bake in 350 degree over 20 minutes or until no longer pink. Remove from heat; cool and shred. Place shredded chicken in a medium bowl, and mix in cream cheese, mayonnaise, cheddar cheese, green chilies, and jalapeno pepper. Transfer the chicken mixture to a medium baking dish. Bake uncovered at 350 degrees for 30 minutes or until edges are golden brown. I use canned chicken. I buy the cans at Sam's. I think they come five to a package. It makes this a little easier to prepare. Very, very good!!