1. Preheat the oven to gas 4, 180°C, fan 160°C. Grease and line 2 cake tins with baking paper. Melt the butter and chocolate in a heatproof bowl over a pan of simmering water. Remove from the heat.

2. Add the sugar to the chocolate and whisk with an electric whisk for 2 mins. Add the eggs and crème fraîche and whisk for 2 mins more until smooth and combined. Fold in the flour, baking and cocoa powders; whisk for 1 min until just combined.

3. Next divide the batter between the tins and bake for 30-35 mins until a skewer inserted in the centre comes out clean. Leave to cool for 10 mins in the tins, then transfer to a wire rack to cool completely.

4. For the decoration, melt 75g chocolate in a heatproof bowl over a pan of simmering water, stirring occasionally until melted. Remove from the heat and set aside to cool for 10 mins.

5. Meanwhile, whisk together the butter, icing sugar and cocoa powder in a large bowl with an electric whisk for 2-3 mins until light and fluffy. Add the cooled melted chocolate and milk, then whisk for 2-3 mins more until smooth.

6. Spoon the icing into a piping bag fitted with a large nozzle, then start piping from the outside edge of one of the upturned sponges in a spiral to the centre. Smooth with a palette knife, then pipe a second layer around the edge.

7. Transfer to a plate and chill in the fridge for at least an hour. Serve and Enjoy!