Prepare the cauliflower mash: Steam or boil cauliflower until cooked. Drain and then mash with your potato masher or blend with the butter, cream, salt and pepper ensuring everything is totally smooth. Set aside.
Cook the beef filling: Heat olive oil or butter in a large skillet. Sauté with onion and garlic. Add beef and cook until browned.
Add vegetables: Add mushrooms, celery and zucchini. Fry for 5 mins until softened.
Make the sauce: Add tomato paste, Worcestershire sauce, beef broth, thyme, salt, and pepper. Simmer for 10 minutes until slightly thickened.
Assemble the pie: Place beef mixture, fresh garlic and cheeze into a baking/serving casserole dish together. Smooth over with the cauliflower mash. If desired add cheddar cheese and cook.
Bake: Preheat oven to 375°F (190°C). Bake for 20 Minutes until the top is golden and bubbly.