Chocolate cake box mix + eggs and oil as per box instructions
250g dark chocolate chips
300ml double cream
3 egg whites
1/2 tsp cream of tartar
2 tbsp caster sugar
180g golden syrup
80g caster sugar
Cut a strip of foil from the roll, just longer than 10 whole (double) Graham crackers. Place the crackers along it in a long thin line, with a 1 centimetre between each one. Fold the foil over and over, so the crackers are covered and you’re left with a long strip. Shape the crackers into a start shape and secure the ends together by squeezing the excess foil together. Put the star onto a flat baking sheet, and press down to get the bottom edge as sealed as possible to the baking sheet. Line the shape with greaseproof paper, as best you can, using baking paper to seal the bottom edges so the cake mixture doesn’t escape. Preheat the oven to 180C / 160C fan.
Make the cake box mix according to the packet instructions, and pour it into the prepared star shape. Bake for 30 minutes, or until a skewer comes out clean. Leave to cool in the tin for 30 minutes then remove the mould and greaseproof paper, and put onto a wire rack to cool. Reserve the Graham crackers for later.
Make the ganache: Once the cake has cooled, make the ganache by putting the chocolate chips into a large mixing bowl, and heating the cream to a gentle simmer. Pour the cream over the chocolate and leave to stand for one minute, then whisk together slowly, from the middle to make sure it doesn’t split.
Put the cake onto a serving plate and use ganache to stick the crackers around the sides. Put into the fridge for 10 minutes, to set. Once the crackers are secured, pour the rest of the ganache on top of the cake, right to the brim, and let a few drips run over the sides. Put in the fridge again for 1 hour or until completely cool.
Make the marshmallow topping not long before you want to serve the cake, after the ganache has set.
Make the marshmallow topping: Put the egg whites, cream of tartar and caster sugar into a stand mixer and whisk to firm peaks. Meanwhile heat the golden syrup and remaining caster sugar in a small saucepan, until it reaches 120C. With the stand mixer running, slowly pour the hot syrup into the egg whites and whisk until light, fluffy and almost cool.
Spoon mounds of marshmallow fluff onto the top of the cake, using the back of a spoon to pull and shape peaks all over it. Use a blowtorch on a low setting to gently caramelise and brown the meringue, then serve.