Cook chicken and shred using two forks.
Cook onion in chicken broth and garlic powder until onion is translucent.
Put all ingredients (except sour cream and whipping cream) in pot and bring to boil.
Reduce heat and simmer for 30 minutes.
Add sour cream and whipping cream. Stir until smooth.
If using crockpot, put all ingredients (except sour cream and whipping cream) into crockpot and cook on 4 hours high or 6 hours low. Take out chicken to shred using two forks. Return chicken and stir in sour cream and whipping cream.