Heat the oven to 180C, 160C fan, gas 4. Grease 2 x 20cm cake tins and line with baking parchment

For the cake; put the chocolate in a bowl and heat in the microwave for around 30 seconds, (keep heating in short bursts if needed), then mix until just combined. In a jug mix 175ml of lukewarm water with the yoghurt, mix around a third of this into the melted chocolate, once combined mix in the rest until smooth. In a separate bowl mix the flour, Baking Powder, Bicarbonate of soda and Cocoa Powder

Cream the butter and sugars until creamy and pale. Gradually beat in the eggs and then gently fold in the flour mixture. Gently fold the chocolate mixture into the cake batter. Divide between the cake tins, smooth the top then bake for 25-30 mins. allow to cool for 20 mins in the tins then transfer to a wire rack to cool completely

For the salted caramel sauce and crunchy topping; (have a baking tray lined with baking parchment ready) put the sugar, liquid glucose and 2tbsp of water in a medium heavy based saucepan over a low heat to melt. Do no stir the mixture, tilt the pan to help combine and if required use a wet pastry brush to help push down any undissolved sugar into the mixture. Meanwhile put the cream in a separate small saucepan and set over a low heat until warm.

Turn up the heat to medium high and bubble the mixture until it is golden caramel coloured (3-4 mins). Take off the heat then add 3 tbsp of the cream, once it stops bubbling add the butter and mix until smooth. Carefully ladle a third of this mixture into the pan with the cream. Add the cornflakes to the caramel mixture in the larger pan and fold with a spatula until evenly coated, spoon into 6 large or 12 small rounds and set of the baking tray to set and cool (around 20 mins). Spray with the gold shimmer spray

Put the pan with the salted caramel sauce back on the heat, add the salt and mix until smooth and glossy. Set aside to cool

For the buttercream; pour 2tbsp of boiling water over the Dark Chocolate, out in the microwave for a few seconds then mix until smooth, leave to cool. Beat the butter and salt in a mixing bowl until soft, add the icing sugar and cocoa powder then beat until smooth. Mix in the melted chocolate then gently mix in the cream cheese

To assemble; put one of the sponges on a serving plate, using a palette knife spread a layer of the buttercream over the top then set the other sponge on top. Spread the rest of the buttercream on top and on the sides of the cake in an even layer. Set the cornflake rounds on top of the cake around the edges then pour the salted caramel sauce into the middle and between the cornflake rounds