Preheat the oven to gas 4, 180°C, fan 160°C.

Grease and line 2 x 20cm cake tins with baking paper.

Melt the butter and chocolate in a heatproof bowl over a pan of barely simmering water. Remove from the heat.

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.

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.

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

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.

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 to make a border.

Stir the jam to loosen, then spoon into the centre of the cake and spread up to the border. Scatter with 50g raspberries, then top with the second sponge. Starting at the base, pipe around in a spiral to cover the sides and top of the cake. Smooth the icing evenly with a palette knife.

Put the chocolate spread in a microwaveable bowl and stir in food colour to reach your desired colour. Microwave for 30 secs, stirring halfway, to melt. Spoon the pink chocolate on top of the cake, using the back of the spoon to help it drip down the sides. Chill for 1 hr to set, then top with 75g raspberries and dust with cocoa powder.

If making the chocolate curls, melt 75g chocolate as in step 1. Spread evenly over a baking sheet and leave to set. Holding both ends of a large sharp knife, carefully drag it horizontally towards you over the chocolate to create curls. Transfer to a plate and chill to harden before arranging on the cake.