Pre-heat the oven to 400F. Peel and wash all root vegetables and cut into chunks. The key is to have similar size chunks so they cook evenly and at the same rate. Onions are the exception and can be quartered or halved (larger) chunks because they cook faster than the other vegetables.
Place all cut root veggies into a roasting pan and add the whole cloves of garlic. Drizzle with olive oil and sprinkle with chopped fresh (or dried) rosemary and sea salt. Place in oven uncovered for 45 to 60 minutes, until the veggies are fork tender and slightly browned on the edges. Serves four.
Note: the beauty of cooking is that you can be creative. For instance, if you can't find celery root, then just use more carrots or parsnips. Don't worry about precise measurements. Cooking can and should be fun, so don't stress over ingredients if you can't find.