Cook sausage, onion and butter until onion is tender. Add celery, carrot, potato, cabbage, broth and salt & pepper to taste.
Bring to a boil. Reduce heat, cover and simmer 10-15 minutes or until potatoes are tender.
Meanwhile, melt butter in a small saucepan. Stir in flour and cook over medium heat about 2 min. Add milk and cream and stir until smooth. Continue whisking until thick and bubbly.
Once vegetables are tender, add cream mixture into the soup. Allow to simmer 5 minutes.
Remove from heat and stir in dill and parsley.