In a two gallon heavy stock pot, heat butter over medium heat. Add onions, bell pepper and garlic, cook for five minutes.
Add spinach and andouille sausage. With a metal spoon, chop spinach into vegetable mixture until it is well incorporated. Sprinkle in flour evenly. Blend it well in to spinach mixture. Stir constantly to avoid scorching
Add chicken stock and oyster liquid, one ladle at a time until all is well blended. Bring to a low boil, reduce to a simmer and cook for thirty minutes.
Add heavy whipping cream, oysters, green onions and parsley. Continue to cook until edges of oysters begin to curl. Season to taste using salt and pepper. Stir in Pernod or Herbsaint.