Cut off and discard pointed tip of garlic bulb, place bulb on a piece of aluminum foil. Fold foil to seal.
Bake at 400° for 1 hour. Cool. Squeeze pulp into a large bowl; stir in whipping cream. Whisk in flour. Set aside.
Layer half of potatoes in a lightly greased 13- x 9-inch baking dish. Sprinkle with 1 teaspoon salt, 1 teaspoon pepper, 1/4 teaspoon nutmeg, and half of cheese. Repeat procedure with remaining potatoes, salt, pepper, and nutmeg. Place baking dish on a jellyroll pan. Pour whipping cream mixture over potatoes.
Bake, covered, at 400° for 30 minutes. Remove cover; sprinkle with remaining half of cheese. Bake 30 more minutes or until potatoes are tender. Let stand 15 minutes before serving.