1.Preheat oven to 180°C. Grease deep 23cm square cake pan, line base with baking paper.
2.Using two packets, prepare cake mix according to directions; pour into prepared pan. Bake about 1 hour. Stand cake in pan 5 minutes; turn onto wire rack to cool.
3.To make butter cream; beat butter until white as possible, gradually beat in half the sifted icing sugar then milk, then remaining icing sugar. Beat until smooth.
4.Using a serrated knife, cut a 3cm slice form one side of cake. Tint butter cream with brown colouring.
5.Spread cut side of large cake with butter cream; place cake, butter cream side down, on 25cm x 35cm rectangular prepared board. Spread butter cream along one end of remaining cake slice; place cake directly in front of large cake.
6.Cut chunks out of top of cake at random. Spread cake and board with butter cream.
7.Wrap matchbox cover with foil, leaving ends open. Dip one end of matchbox in combined icing sugar and drinking chocolate, press gently into butter cream to form brickwork pattern.
8.To make telegraph pole, place one flake on a piece of baking paper, cut remaining flake in half. Secure half of flake on one end of whole flake with a little milk chocolate. Secure mint stick to flake with a little more chocolate. Leave to dry before attaching to board with a little more chocolate.
9.To make the mice, tint white chocolate grey with black colouring. Pipe mice shapes onto piece of baking paper, leave to set. Pipe eyes, ears and nose with little milk chocolate.
10.Using yellow decorating icing, pipe a “paint splash” on wall. Pipe graffiti on remaining wall with white decorating gel.
11.Tint coconut with white colouring, sprinkle coconut around base of cake. Using picture as a guide, spread crushed boiled sweets over board to resemble broken glass. Arrange mice and toys of your choice around wall.
Personalise the messages scrawled all over this clever cake, which looks just like an inner-city wall for the cake.Note