1. Combine melted butter, zwieback crumbs, brown sugar, orange peel, mace, and salt; mix well.
2. Arrange pears, cut side up, in a shallow baking dish; fill hollows of pears with crumb mixture.
3. Pour 1/2 cup of the reserved pear syrup around pears; cover with aluminum foil.
4. Bake at 350°F 15 minutes; uncover and bake 15 minutes longer, or until crumbs are browned.
5. Serve warm with Plantation Orange Sauce.