Take one head cauliflower, cut into chunks and boil until tender. Drain very well and set aside. Saute 1/4 diced onion until soft, add 2 cloves diced garlic and 1/2 tsp thyme and saute another 2 minutes. Turn off heat and set aside. Place cauliflower in a large bowl with 4 oz cream cheese, softened, and 2 or 3 tbsp heavy cream and blend with hand mixer. Add onion mixture, 1/2 cup shredded mozzarella cheese and salt and pepper to taste to cauliflower and stir until blended. Spray an 8 x 8 casserole dish with nonstick spray and pour in cauliflower. Sprinkle another 1/2 cup mozzarella cheese on top and bake 15 to 20 minutes at 400 degrees. Once it is cooked, turn on broiler and broil casserole until golden brown, around 3 minutes.