Start with a 20cm / 8 inch round cake tin, greased and lined with baking parchment. Preheat the grill to medium temperature. Beat the egg yolks, butter, icing sugar, plain flour, cornflour and baking powder together until light and fluffy. 

In a separate bowl, whisk the egg white until stiff peaks form, then gradually add in the caster sugar and mix. 

Fold the egg mixture into the cake mixture. Then divide evenly between the two bowls. 

Add the cocoa powder into one bowl and stir until combined. Add the vanilla bean paste and green food colouring to the second bowl and mix well until combined. 

Spread two heaped tablespoons of chocolate mixture into the cake tin. Cook under the hot grill for one to two minutes until the batter is cooked. It should feel firm to the touch and small bubbles will appear. 

Remove from the grill, then spread two heaped tablespoons of the green cake mixture on top. Place it back under the grill for another one to two minutes. Repeat this process alternating the two cake mixtures. There should be about 16 layers in total. Once all layers are cooked, allow the cake to cool for 15 minutes, then carefully remove it from the cake tin and leave it to cool completely onto a wire rack. 

For the chocolate sauce, break the milk chocolate into small pieces into a heat proof bowl along with the unsalted butter. Place over a saucepan of simmering water and stir until melted. 

Turn the cake upside down and place onto a cake board or plate. Spread the warm chocolate sauce all over the cake. Place into the fridge until the chocolate topping has set. 

To decorate the cake, follow the instructions on the pack over the fondant icing to cover the cake. Trim the icing around the sides of the cake. Roll the trimmed icing into a ball, add the black food colouring gel and knead. This will get sticky so add some cornflour to your hands. 

Cut two tear drop shapes for eyes, two bean shapes for the nose and roll three 20cm long thin strips. Use one for the mouth, then cut the remaining into 2cm pieces to make the stitches. To finish cut out eight rectangle shapes 3cm in width and 6cm in length. Dab a small amount of water on the back of the icing to stick these to the cake.