This hearty dish tastes like beer cheese soup. Tart Granny Smith apples work best, but you can substitute other firm-textured apples. Choose a hearty, aged cheddar cheese; it won't get stringy when it cooks.
Heat oven to 350 degrees. Spread softened butter evenly in 8-cup sallow gratin or baking dish.
Place beer, cream, onion, salt, pepper and garlic in large saucepan or dutch oven; stir in potatoes. Bring to a gentle boil over medium heat; cook 5 minutes or until liquid is thickened, stirring constantly. Stir in rosemary.
Spread half of the potato mixture over bottom of gratin dish; top with apples. Sprinkle 1 1/4 cups of the cheese over apples. Layer remaining potato mixture over cheese.
Cover dish with foil. Bake 30 minutes; remove foil. Sprinkle with remaining 1/4 cup cheese. Bake 30 to 40 minutes or until potatoes and apples are tender, liquid has thickened and top is lightly browned. Remove from oven; let stand 10 minutes.