Preparation Preheat oven to 350°F. Butter 13x9-inch oval gratin dish. Whisk broth, flour, rosemary, salt, and pepper to blend in heavy large saucepan. Bring to boil, whisking frequently. Add potatoes and bring to boil. Transfer half of potato-broth mix to prepared dish. Sprinkle with 3/4 cup cheese. Top with remaining potato-broth mix. Cover with foil and bake 30 minutes. Uncover; sprinkle with remaining 3/4 cup cheese. Continue baking uncovered until potatoes are tender and top browns, about 45 minutes. Cool slightly.
Preparation Preheat oven to 350°F. Butter 13x9-inch oval gratin dish. Whisk broth, flour, rosemary, salt, and pepper to blend in heavy large saucepan. Bring to boil, whisking frequently. Add potatoes and bring to boil. Transfer half of potato-broth mix to prepared dish. Sprinkle with 3/4 cup cheese. Top with remaining potato-broth mix. Cover with foil and bake 30 minutes. Uncover; sprinkle with remaining 3/4 cup cheese. Continue baking uncovered until potatoes are tender and top browns, about 45 minutes. Cool slightly.