1.Preheat oven to 180°C. Grease deep 26cm x 33cm baking dish; line base and sides with baking paper, extending paper 5cm above sides.
2.Make cakes according to directions on packets. Pour mixture into dish; bake about 1 hour. Stand cake in dish for 20 minutes before turning, top-side up, onto a wire rack to cool.
3.Dissolve jellies in a large heatproof bowl using 3 cups of boiling water and 2½ cups cold water. Refrigerate until set.
4.Using a serrated knife, level cake top. Turn cake cut-side down. Using the picture as a guide, cut jellyfish shape from cake. Place in 35cm x 45cm shallow plastic tray.
5.To make butter cream, beat the butter (and any flavouring, if using) in a small narrow bowl with an electric mixer until the butter is as white as possible (this will result in a whiter butter cream which will give you better results if colouring it).
6.Gradually beat in half the sifted icing sugar then the milk, then the remaining icing sugar. Beat until the butter cream is smooth and spreadable. Keep scraping down the side of the bowl during beating.
7.Tint butter cream mauve. Spread butter cream over top and sides of cake.
8.Position white Melts on cake for eyes; secure SMARTIES to top of Melts with a little butter cream.
9.Using the picture as a guide, decorate cake with WONKA NERDS.
10.Using whisk, break up jelly; spoon carefully into tray around cake.
11.Cut WONKA NERDS Ropes in half; position below cake as tentacles. Pinch ALLEN’S Milk Bottles to form a fish shape; position in jelly.
Equipment: deep 26cm x 33cm baking dish; 35cm x 45cm shallow plastic tray. You need the large shallow tray to hold the cake and jelly. Refrigerate the cake if the weather is hot. Vanilla Milk Bottles can be found in ALLEN’S Retro Party Mix, Party Mix, Classic Party Mix, Teeth `n’ Stuff and Milk Bottle Mania.