Preheat oven to 400 F.

Add cauliflower to a pot, fill with water and cover.

Bring to a boil over medium-high heat and cook until florets are fork tender, 8 to 10 minutes.

Drain well, add ghee, and season to taste; mash until smooth using a potato masher.

Melt cooking fat in a skillet over medium heat.

Add the onion, celery, garlic, and cook 2 to 4 minutes; stirring often.

Add the ground beef and cook until browned, 4 to 5 minutes.

Add the mushrooms and continue cooking until mushrooms are soft.

Pour in the beef stock and season to taste, cook 4 to 5 minutes longer.

Place the beef mixture in a casserole dish and top with the mashed cauliflower.

Bake 15 to 20 minutes, or until the mashed cauliflower is nicely browned.

Serve topped with fresh parsley.