The lava shapes are best made and used on the day of serving as they become slightly sticky after a while.
Preheat the oven to 180C/160C fan/gas 4. Grease and base line an 18cm round cake tin, a 800–900ml oven proof (Pyrex) bowl and a 1.2 litre oven proof bowl.
Put the butter, 300g of the sugar, eggs, flour and milk into a large bowl and beat well until light and creamy. Spread just under half the mixture in the cake tin.
Take just under half of the remaining mixture and put into a bowl and colour deep red with food colouring. Put 3–4 small spoonfuls of red cake mix onto the mixture in the cake tin. Using the handle of a teaspoon pull the red mix through to give a marbled effect.
Using the remaining plain and red cake mix place spoonfuls in a random fashion in the two prepared bowls. Again use the teaspoon handle to give a marbled effect.
Bake in the oven for about 30 mins for the small bowl, about 35 mins for the medium and 50–60 mins for the cake tin. The mixture is cooked when firm to the touch and when a skewer inserted into the centre comes out clean.
When the cakes are cold trim off any peaks that have formed. Place the round cake on a large cake board. Cut three small ‘v’ shapes on the edge of the cake, to make an uneven shape for the volcano base. Spread a little apricot glaze all over the cake and place the larger bowl cake, rounded side up, on top. Brush with apricot glaze and place the remaining cake, rounded side up, on top. Cut a small hollow in the top of this cake (to represent the ‘mouth’ of the volcano) and then brush the cake with apricot glaze.
Roll out the marzipan to a large circle to cover the cake. It can be quite a rough shape. Lift it onto the cake and drape in a random fashion in the nooks and crannies to make a volcano shape.
Melt the chocolate in a microwave or in a bowl over a pan of hot water. Using a pastry brush, paint the volcano with chocolate. Attach chunks of chocolate, popcorn etc with melted chocolate. Add the dinosaurs. Drizzle any remaining chocolate over the volcano in a random fashion.
To make the lava put the remaining 50g sugar into a small non-stick frying pan. Heat gently without stirring until the sugar has melted but is still clear. Lightly oil a metal baking sheet. When the sugar is just turning light brown at the edge, remove from the heat and carefully stir in a little red paste food colouring. Using a teaspoon, drizzle lava shapes onto the prepared tray. Leave to cool completely.
When cold, carefully lift the lava shapes and place in the top of the volcano. For extra effect use birthday candles, cake sparklers, or cake fountains.