Gochujang chocolate fudge cake

Preheat the oven to 180ºC, gas mark 4. Grease and base line 2 x 18cm cake tins with baking parchment. Melt the chocolate in a heatproof bowl over a pan of just-simmering water (or in the microwave). Set aside.

Meanwhile, in a large bowl, sift together the flour, cocoa, bicarbonate of soda, baking powder and a pinch of salt. In a separate bowl, use an electric hand mixer to cream the butter and both sugars for about 2 minutes until combined and slightly pale. Gradually add the eggs, mixing well between each addition. Add the melted chocolate and mix with a spatula until just combined.

Bring a kettle to the boil. Beat ⅓ of the sifted dry ingredients into the batter followed by ½ of the soured cream. Continue adding alternate batches of dry ingredients and soured cream; mix until smooth. Add the gochujang and mix to combine. Pour in 90ml just-boiled water, mix until combined, then divide the mixture evenly between the prepared tins and level out with a palette knife. Bake for 25 minutes until risen and a skewer inserted into the middles comes out clean. Set aside to cool.

Meanwhile, make the buttercream. Put the caster sugar in a small, heavy-based pan with 1 tbsp water. Set over a low-medium heat to dissolve the sugar without stirring. Once the dissolved, increase the heat slightly and continue to cook until it becomes an amber-coloured caramel. Take the pan off the heat and carefully add the soured cream and orange juice. Stir to combine, return the pan to the heat and bring back to the boil, stirring to melt any hardened lumps of caramel. Cook for 2-3 minutes until the caramel has reduced by about ⅓ and is the colour of toffee. Pour into a bowl, add the sea salt and ½ tsp orange zest, then set aside to cool before chilling until completely cold.

When ready to assemble, take the caramel out of the fridge. Put the chocolate in a heatproof bowl and melt over a pan of gently simmering water (or in the microwave); set aside. In a large bowl using an electric hand mixer, beat the butter for 1 minute until pale and light. Mix in the caramel, then sift in the icing sugar in 3 batches and beat until the buttercream is light and fluffy. Stir in the melted chocolate. Place 1 cake on a serving plate; spread the top with ½ of the buttercream. Place the second cake on top and spread with the remaining buttercream. Chill for 30 minutes. Serve the cake scattered with grated dark chocolate curls, remaining orange zest and some extra sea salt flakes, if you like.