Preheat the oven to 180°C/350°F/Gas 4 Grease and line a rectangular cake tin (20 cm x 28 cm) with non-stick baking paper

Tip the contents of both packets of cake mix into a mixing bowl, add the eggs and 10 tbsp water and, using an electric whisk beat for 1 minute until smooth and creamy.

Spoon the mixture into the prepared cake tin level it off and bake for 35 to 40 minutes until springy to the touch. Allow to cool on a wire rack Once cooled, trim the sides to form a coffin shape then carefully slice in half horizontally. Spread one half with the jam and one half with the chocolate spread, sandwich together and lift onto a board or plate.

While the cake is cooling, knead a few drops of black food colouring into the fondant icing until it becomes evenly gray.

Roll out the gray fondant on a clean surface, lightly dusted with icing sugar, to a rectangle large enough to cover the top and sides of the cake. Carefully lift the icing over the cake and use your hands to smooth it over the top and sides of the cake. Trim the edges neatly. Re-roll any trimmings and cut out a small rectangular plate to go on top of the coffin and use the red writing icing to pipe the letters RIP onto it

With a steady hand pipe a cobweb using the black icing, and pipe borders and edges to the coffin and plate. Use your chosen decorations to place on and around the cake.