Preheat oven to 425 degrees F.
Mix amaretto and vinegar in a 13 by 9-inch baking dish. Put pears, cut sides down, in dish.
Roast pears 15 minutes. Add water and roast until pears are tender but still hold their shape, 8 to 10 minutes more.
Arrange pears, cut sides up, on a platter and spoon pan juices over them. Sprinkle with half of cookie crumbs, then baste with pan juices. Sprinkle with remaining crumbs and serve warm or at room temperature.