Peel carrots and store in cold water until ready to cook. Wash and scrub beetroot and turnips. Pat vegetables dry. In a bowl, toss with 1 tbsp olive oil until well covered. Preheat oven to 190C. Place beetroot in ovenproof dish, sprinkle with salt, roast 12-15 minutes until tender. You should be able to pierce with a sharp knife with a little resistance. Heat remaining oil in ovenproof pan on high. Lightly colour carrots and turnips for a minute. Sprinkle with salt and transfer to oven for 8-10 minutes, until tender. Remove and keep warm. Bring cream to boil, reduce heat to a simmer and add parmesan. Stir and continue simmering 3-5 minutes until it thickens. Remove from heat, stir in butter then a third of truffle, grated. Spoon some sauce on to six warm plates and scatter vegetables on top. Shave remaining truffle thinly over vegetables (pictured).