Prepare the chicken by cutting off any excess fat from the chicken breasts. Cut the chicken into bite sized pieces. In a large saucepan bring the pot to medium-high heat. Add the olive oil and then the chicken pieces. Let the chicken start to cook while you cut the onions. Add the onions to the chicken and then season with the garlic powder, salt, pepper, cumin, oregano, cayenne pepper. Once the chicken seems to be mostly cooked, add the drained beans, broth and chilies. Bring to a boil. Reduce heat; simmer, uncovered for 30 minutes. Remove from the heat; stir in sour cream, cilantro and milk or half & half. Garnish with more fresh cilantro, if desired. Serve with tortilla chips and more sour cream.