1. Set puff pastry out to thaw. Preheat oven to 400°F. Peel potato, rutabaga, parsnips, and carrots; cut each into ½-inch-thick rounds.
2. Smash garlic. Cut onion into ½-inch-thick rounds. Remove rosemary leaves from stems. Slice chives thinly. Remove rind from Brie if desired; cut Brie into ¼-inch-thick slices, then into 1-inch squares.
3. Divide potatoes, rutabagas, parsnips, carrots, garlic, and onions between 2 baking sheets. Drizzle with oil and sprinkle with Greek seasoning; stir until well coated, then spread into single layer. Bake 20 minutes, then remove from oven and let stand to cool 10 minutes.
4. Meanwhile, place sugar and water in medium saucepan on medium. Cook 5–7 minutes without stirring until mixture boils and sugar is amber in color. Remove pan from heat; stir in vinegar, black pepper, and red pepper. Pour caramel quickly and evenly into 13- x 9-inch baking dish.
5. Sprinkle rosemary over caramel. Arrange vegetable rounds cut-side down in single layer over caramel. Top evenly with onions, garlic, and Brie.
6. Dust work surface with flour. Roll pastry into 13- x 9-inch rectangle; cover vegetable mixture with pastry, tucking in edges if needed. Bake 20 minutes.
7. Reduce heat to 375°F. Bake 10–15 more minutes until top is golden and vegetables are tender. Let stand 10 minutes before inverting carefully onto large serving dish. Sprinkle with chives; slice and serve

Chef's Tip: if rutabaga or parsnips aren't your favorite vegetables, add additional sweet potatoes, carrots or gold potatoes in there place.