Preparation Preheat oven to 375°F. Wrap beets in foil; bake until center is tender when pierced with knife, about 1 hour 45 minutes. Cool. Peel; cut each beet into 8 wedges. Cook brussels sprouts in pot of boiling salted water until crisp-tender, about 6 minutes. Using large slotted spoon, transfer brussels sprouts to bowl of ice water; cool. Drain. Add turnips to pot; boil until crisp-tender, about 7 minutes. Drain. Transfer to bowl of ice water; cool. Drain. (Can be made 1 day ahead. Cover; chill.) Melt butter in heavy large deep skillet over medium-high heat. Add shallots and hazelnuts; sauté until nuts begin to brown, about 3 minutes. Add thyme and garlic; sauté until nuts are golden, about 2 minutes. Add all vegetables; cover and cook until heated through, stirring occasionally, about 5 minutes. Season with salt and pepper. Transfer to bowl and serve.
Preparation Preheat oven to 375°F. Wrap beets in foil; bake until center is tender when pierced with knife, about 1 hour 45 minutes. Cool. Peel; cut each beet into 8 wedges. Cook brussels sprouts in pot of boiling salted water until crisp-tender, about 6 minutes. Using large slotted spoon, transfer brussels sprouts to bowl of ice water; cool. Drain. Add turnips to pot; boil until crisp-tender, about 7 minutes. Drain. Transfer to bowl of ice water; cool. Drain. (Can be made 1 day ahead. Cover; chill.) Melt butter in heavy large deep skillet over medium-high heat. Add shallots and hazelnuts; sauté until nuts begin to brown, about 3 minutes. Add thyme and garlic; sauté until nuts are golden, about 2 minutes. Add all vegetables; cover and cook until heated through, stirring occasionally, about 5 minutes. Season with salt and pepper. Transfer to bowl and serve.