Beat the softened butter till very light and fluffy. Add the sifted sugar and salt and beat till very light. Around 10 minutes. Beat in the melted cooled chocolate gradually. Add a squeeze of lemon ( 2 teaspoon, this will even out the flavour)
Use a cake board or a cake stand. To rest your cake on. Start to add your buttercream adding an equal amount for each layer, approximately 1 x 1 1/2 cups ( for a bigger cake).
Continue like this till the layers are finished.
Cover with a very thin coat of buttercream. Chill for 15 minutes and then cover with another thin layer if there is some left. chill if the weather is hot. You can cover a cake base with red icing if you like. Knead till soft . Sprinkle the bench lightly with icing sugar. Spread the board with a spoon of buttercream to help the icing stick. Roll out 1/2 of the red icing in a thin round and fold over the rolling pin onto the cake. Trim the edges. Add a little more buttercream to the iced board and gently put the cake into the middle of it.
Knead the 3/4 white plastic roll out icing ( the remainder is for the eyes) till soft and then start to add some blue colouring ( approx 1/2 teaspoon) Knead till smooth and evenly coloured. Sprinkle a clean bench with icing sugar ( no lumps) . Measure the size of the cake from side to side and across the top so you know how big to roll out the icing. Try not to get too much icing sugar on the icing as it will show on the finished cake. Roll the icing out fold over the cake smoothing down with an icing smoother or clean teatowel
Next make the spider man head. ( watch the video)
You will need to make the head, the buildings and the eyes.
The recipe for royal icing is 1/2 an egg white , 1/4 teaspoon lemon juice and approximately 1 cup of pure sifted icing sugar added gradually and mixed till smooth. It needs to be the consistency of toothpaste . if too thin add more to the mixture. This can be used as glue to stick decorations onto the cake and as the tiny white windows on the cut out buildings.