In a large skillet over medium heat, melt butter. Add sausage, onion, carrot, and celery and cook until sausage is done and vegetables are soft, 7 to 8 minutes.
Add cauliflower and mushrooms and season with salt and pepper. Cook until tender, 8 to 10 minutes more.
Add parsley, rosemary, and sage and stir until combined. Pour over broth and cook until totally tender and liquid is absorbed, 10 minutes.
