1Heat oven to 400°F. Cut each apple in half lengthwise; scoop out seeds and cores.
2Spoon about 1 tablespoon yogurt into each of the apple centers. Sprinkle with nutmeg. Place filled apples in ungreased 13x9-inch (3-quart) baking dish. Pour water into baking dish until half full.
3Bake 30 to 40 minutes or until apples are tender. Set oven control to broil. Top each apple with marshmallow half. Broil apples with tops of marshmallows 4 to 6 inches from heat about 30 seconds or until marshmallows are golden brown. Serve warm.