Queen Ranch Chicken

• 1 onion (chopped)
• 400 gr stewed tomatoes (canned)
• 350 ml broth
• 200 gr chicken
• 60 gr velvetta cheese cubed
• 20 gr lite margarine
• 12 gr cornstarch
• 1 1/2 packages chicken broth
• 1 package green chilies (drained)
• some garlic powder