Greg Rutherford's salted caramel and peanut brittle showstopper recipe

Make the cake

1. Heat oven to 180°C/160°C fan/gas mark 4. Grease 2 x 20cm x 4.5cm deep cake tins with plenty of butter, and line the bases with baking paper. Boil the kettle.
2. Measure all the ingredients for the cake into a large mixing bowl and, using an electric whisk or wooden spoon, beat together until smooth.
3. Measure 250ml of boiling water into a jug and add to the cake batter a little at a time, beating well after each addition.
4. Divide the mixture between the cake tins and bake for 25-30 minutes, or until a skewer inserted into the centre comes out clean.
5. Leave the cakes to cool in their tins, on a wire rack.

Make the icing

Put the sugar, double cream and 80g of the butter into a saucepan and set over medium heat. Allow the butter to melt, then turn up the heat and bring to the boil – stirring constantly. Allow to boil for 1-2 minutes, then remove from the heat and leave the butterscotch sauce to cool completely.

Make the peanut brittle topping

1. Oil a lipped baking tray and set aside.
2. Put the sugar and 2 tbsp water into a small saucepan. Set over a low heat and allow the sugar to dissolve - do not stir.
3. Once the sugar has completely dissolved, turn up the heat and bring to the boil. Let it bubble and turn a dark amber colour – this could take 10-20 minutes, watch over it at all times.
4. When it reaches dark amber throw in the peanuts and stir to coat them with the caramel, then quickly pour onto the greased baking tray and leave to cool until solid.

Top tip: Never stir the caramel when it's boiling, but you can swirl the pan around. If your caramel crystalizes and goes all grainy, throw it away and try this video for how to make caramel.

Once the butterscotch sauce is completely cool finish making the icing

1. Put the remaining butter into a bowl and, using an electric whisk, beat until pale and fluffy – you could also do this in a freestanding mixer using the whisk attachment.
2. With the whisk still going, gradually pour in the butterscotch sauce and continue whisking until the icing is light and pale in colour.
3. Finally, stir through the salt.

Assemble the cake

1. Place one of the chocolate sponges onto a cake stand, then spread over half the butter-cream icing.
2. Gently place the other cake on top and spoon over the remaining butter-cream, creating swirls as you go.
3. To finish, put the peanut brittle into the small bowl of a food processor and roughly blitz to create your sand, then sprinkle on top of the cake to create a ‘long jump pit’.
4. You could also pile the blitzed brittle in the centre of the cake or scatter it evenly over the surface.