Great British Bake Offchamp John Whaite has created an unbelievably moist and decadent cake that can only be described as ‘a show-stopper’.

• 125ml sunflower oil, plus extra for greasing
• 7 large eggs, separated
• 2 tsp vanilla bean paste
• 375g golden caster sugar
• 50g cocoa powder
• 300g plain flour
• 200ml water
• 1 tsp bicarbonate of soda
• 1 tsp salt

For the salted caramel icing

• 250g light soft brown sugar
• 150ml double cream
• 140g butter, softened
• ½ tsp salt

For the ganache

• 250ml double cream
• 250g dark chocolate, finely chopped or grated
• Sea salt crystals

Method

1   Heat oven to 160°C/140°C fan/gas 3. Grease and line a 25cm round deep cake tin with baking parchment. In a large bowl, mix the oil, egg yolks, vanilla paste, caster sugar and water until well combined. Sift in the cocoa powder and whisk until smooth.

2   Sift in the flour, bicarb and salt. In a separate bowl, whisk the egg whites to stiff peaks. Fold into the batter with a large metal spoon and mix until everything is well combined.

3   Gently pour the mixture into your cake tin, then bang it on the work surface twice to expel any large air pockets. Bake for 1 hr 10 mins or until the cake springs back when gently prodded and an inserted skewer comes out clean. Cover with foil after 1 hr if the cake starts to get too dark.

4   While the cake bakes, make the salted caramel icing. Heat the brown sugar, salt and cream in a saucepan until the sugar has dissolved. Bubble for a few mins, then leave to cool. Beat the butter until smooth, pour in the cooled cream mixture and continue mixing until softly whipped. Chill until needed.

5   When the cake is baked remove it from the oven, cool in the tin for 10 mins, then transfer to a large wire rack and peel off the parchment. Leave until completely cool.

6   To make the ganache, heat the cream until just boiling. Remove from the heat and pour over the chocolate. Leave to stand for a few mins until the chocolate has melted and you have a smooth sauce consistency.

7   To finish, slice the cake in half and fill with the salted caramel buttercream. Spoon the chocolate ganache over the top and decorate with the sea salt crystals.