Rub a shallow 2-quart baking dish liberally with cut clove of garlic, then generously grease with about 1/2 tablespoon of the butter.
In a bowl, combine the lemon juice and water. Peel the potatoes, if desired, and cut into very thin slices; place in the lemon water until all are sliced.
Drain potatoes well and arrange about 1/4 of the slices in an even layer in the prepared dish; sprinkle lightly with salt and pepper, then top with about 1/4 of the onions and of the cheese. Repeat layers, ending with cheese.
Heat beef broth, then slowly pour over and around the potatoes. Dot top with remaining 2 tablespoons butter.
Bake, uncovered, in a 350° oven for 1 1/2 hours or until potatoes are tender when pierced.