In a large pot, melt butter or margarine. Add garlic and cook over medium heat for 2-3 minutes. Add cream cheese and milk or cream. Stir until cream cheese is completely melted. Do NOT boil.
Stir pasta, spinach and seasonings into the pot until combined. Pour half of the mixture into a round or square casserole dish. Cover with half the mozzarella cheese. Add remaining pasta and top with remaining cheese.
Bake at 350 degrees for about 20 minutes, until cheese if fully melted and lightly browned on top.