In a large skillet, melt butter over low-medium heat, stirring often to prevent burning. Add onion, carrot, celery, and garlic. Cook for about 10 minutes, stirring often.
Add cauliflower, cook, and stir often for an additional 5 minutes over medium heat.
Add chopped mushrooms and salt and pepper. Cook and stir often for 4 more minutes.
Add sage, thyme, rosemary, poultry seasoning, parsley, broth and bring to a boil over high heat. Reduce heat and simmer 5 minutes or until liquid is absorbed and the cauliflower is tender.