Preheat oven to 375. Place garlic in a small baking dish; drizzle oil over. Bake until garlic is very tender and brown in spots, about 45 minutes. Cool briefly. Transfer garlic to work surface; reserve oil in dish. Peel garlic and chop coarsely. Increase oven temperature to 400. Brush 13 x 9 x 2 glass baking dish generously with reserved garlic oil. Using a food processor fitted with a four millimeter slicing disk, cut potatoes in thin rounds. Layer potatoes in prepared dish, sprinkling each layer with chopped garlic, thyme, nutmeg, salt and pepper. Overlap slices for top layer in a decorative pattern, if desired. Bring broth and cream to a boil in heavy medium saucepan. Pour broth mixture over potatoes. Cover dish with aluminum foil. Bake potatoes for 45 minutes. Uncover and bake until potatoes are tender and brown on top and liquids thicken, about 45 minutes longer. Let stand 10 minutes. Sprinkle additional thyme over potatoes and serve.