Preheat oven to 350°.
Melt margarine in a large skillet over medium-high heat; add 2 cups chopped apple, and sauté 5 minutes. Stir in currants, rum, and brown sugar, and cook 1 minute. Set aside.
Core 4 apples, cutting to, but not through, bottoms. Enlarge cavity of each apple by cutting out about 1 inch around inside of core. Peel top half of each apple. Place apples in an 8-inch square baking dish. Spoon 1/2 cup apple mixture into center of each apple. Pour maple syrup and cider over apples; cover dish with foil. Bake at 350° for 15 minutes. Remove from oven; uncover dish.
Beat the egg whites at high speed of a mixer until foamy. Add granulated sugar, 1 tablespoon at a time, beating until stiff peaks form. Spoon the mixture into a pastry bag fitted with a star tip. Pipe the egg white mixture onto tops of apples. Bake the apples at 350° for an additional 20 minutes or until lightly browned. Serve baked apples with sauce.
Note: A heavy-duty zip-top plastic bag can be used instead of a pastry bag. Spoon egg white mixture into bag; Snip 1 bottom corner of bag for opening.