GF White Chicken Chili

1 medium onion, chopped
1 T olive oil
2 cloves garlic, minced
2 cups chopped cooked chicken breast
2 cans (14oz) chicken broth
1 can 4oz diced green chilis
2 t cumin
2 t oregano
3 cans 15 oz Great Northern Beans
shredded cheese

Saute the onion in the oil until tender.  Add remaining ingredients except cheese.  Bring to bil.  Reduce heat and simmer 20-30 minutes.   Garnish with cheese if desired