1. Trim the crusty edges from the cake. Using a ghost-shaped cardboard template, cut out 4 shapes.
2. Slice each shape in half through the middle and sandwich back together using the cherry pie filling.
3. Spread the top of each cake thickly with the white frosting, and place chocolate chips on the top to resemble eyes and a mouth.
4. Dust serving plates lightly with cocoa powder and place a ghost cake on top of each to serve.