White Chili

1 white onion
4 can breasts
6 garlic cloves
oil
3 cans white beans
5 ckn bouillon
1 tsp salt
1/2 tsp pepper
1 cup sour cream
1 tsp cumin
1 tsp oregano
1/4 tsp cayenne
3/4 cup milk
1 can chopped green chilies