Melt the butter in a large pot over medium heat.
Add the celery, carrot, mushrooms and garlic and cook for 3 to 4 minutes, until fragrant and starting to soften.
Pour in the bone broth and add the parsley, onion powder, salt and pepper.
Bring to a simmer, then lower the heat to medium-low.
Simmer for 10 to 15 minutes, until the carrots and celery are tender.
Add the shredded chicken and the sliced cabbage.
Cook for about 10 minutes more, until the cabbage is tender but still has some bite. Do not let it go soft.
Taste for salt and serve hot.
