1.Preheat oven to 180°C/350°F. Grease pans; line base with baking paper.
2.Make cakes according to directions on packets; pour evenly between pans to the same depth. Bake about 35 minutes. Stand in pans 5 minutes; turn onto wire racks to cool.
3.Using a serrated knife, level cake tops; turn cakes cut-side down. Using picture as a guide, cut out soda glass from loaf cake by cutting at a slight angle from top corners of the cake. Place cakes, cut-side down, on cake board.
4.On surface dusted with icing sugar, knead 290g of the ready-made icing until smooth; tint red. Roll out until large enough to cover loaf cake. Cut one side of the icing straight. Carefully lift icing onto cake, placing the cut side 3cm below the top edge of the cake. Gently mould icing over cake; trim edges. Brush ¼ cup of the jam on the uniced part of the cake.
5.Roll 10g of ready-made icing into a 20cm long cord. Position at top of soda glass to create a rim on the glass, trim ends.
6.Rinse icing sugar off turkish delight; pat dry with absorbent paper. Cut each piece into small cubes; press onto jam at top of soda glass. Push in curly straw.
7.Decorate glass with cake stars. Using white decorating gel, pipe a swirl onto soda glass.
8.Roll 200g of ready-made icing into a 5cm x 80cm rectangle; lift and place around edge of round cake. Using hands dusted with icing sugar, gently mould icing over edge of cake, trim edge. Using a small knife, cut unevenly into icing on top of round cake. Blend cocoa powder with water in a small bowl; brush over icing for pizza crust.
9.Spread remaining jam in centre of round cake.
10.Place a few drops of yellow colouring in a small bowl with 2 teaspoons of water. Add coconut; toss gently to colour unevenly. Scatter coconut over jam on round cake for cheese; position jelly beans and strawberries. Cut karate belt into curvy strips; place randomly on pizza cake.