In a small saucepan, cook the apple, brown sugar, cinnamon, and nutmeg over a medium-low heat until softened. Remove and cool, then mix in some toffee sauce.
Cut three thin strips on a chilled sheet of puff pastry. Cut two of the strips into four and make a small lattice pattern with them. Repeat to make three more lattices.
Cut the tops of the apples and scoop out the insides carefully with a melon baller. Fill with the toffee apple mixture.
Place the lattices on top of each apple and drape the remaining strips around the lattice, cutting off any overhang.
Place apples in an ovenproof dish, brush the pastry with egg wash and sprinkle over some more brown sugar and cinnamon. Bake for 20 minutes.
Serve with ice cream and more toffee sauce. Enjoy.