Preheat the oven to 170˚C (150˚C fan oven, 325˚F, gas 3). Grease and line 2 x 7cm (3inch) deep, 18cm (7 inch) diameter round cake tins.

Break the Extra Dark Chocolate into pieces and place in a large saucepan and add the butter, sugar and Cocoa Powder. Place over a very gentle heat, and leave to melt, stirring occasionally. Remove from the heat and stir in the hot coffee. Leave to cool for 10 minutes.

Sift the flour, Baking Powder and Bicarbonate of Soda into a large bowl and make a well in the centre.

Whisk the eggs and Vanilla into the chocolate mixture, then gradually pour into the centre of the dry ingredients, mixing all the ingredients together until everything is well blended together and there are no pockets of flour.

Divide the mixture equally between the prepared tins. Put the tins on a baking tray and bake in the oven for about 50 minutes until risen and lightly crusted on top – a skewer inserted into the centre of the cakes should come out with a few crumbs sticking to it. Note: slightly undercooking the cake gives a dense "mud-like" texture to your cake, and it will sink slightly as it cools; if you prefer a spongier texture, cook for 1 hour until risen and just firm to the touch. Cool for 10 minutes before removing from the tins and transferring to a wire rack to cool completely, upside down. Carefully slice through the middle of each cake to create 4 equal cake slices.

To decorate, break up 200g (7oz) Extra Dark Chocolate into a large heatproof bowl. Put the bowl over a saucepan of barely simmering water and leave to melt. Remove the bowl from the saucepan and leave to cool for about 10 minutes until warm but not hot.

Whilst whisking the chocolate, gradually pour in the cream, whisking until thick and glossy. Sandwich the 4 layers of cake together using the chocolate cream, leaving the top uncovered. Leave in a cool place whilst preparing the topping. If the room temperature is warm, pop the cake in the fridge for up to 20 minutes.

Break up the remaining Extra Dark Chocolate and place in a saucepan with the butter and 20ml (4 tsp) water. Heat very gently, stirring occasionally, until melted and smooth. Remove from the heat and set aside for about 15 minutes to cool and thicken.

Once thickened, spoon the melted mixture over the top of the cake and smooth the mixture right to the edge of the cake using a palette knife, allowing it to drip over the edge. Leave to stand in a cool place for several minutes to allow the chocolate to set. If the room temperature is warm, pop the cake in the fridge for up to 20 minutes.

When ready to serve, decorate the top generously with chocolate curls and shavings. Your cake is now ready to serve and enjoy!

Once chilled, the chocolate cream and ganache will set firm. Prolonged chilling of this cake will dry out the texture.

Break 50g (2oz) Dr Oetker Fine Cook's 72% Extra Dark Chocolate and 50g (2oz) Dr Oetker Fine Cook's Milk Chocolate into pieces and place in a heatproof bowl. Put the bowl over a saucepan of barely simmering water and leave to melt. Remove from the water and mix well.

Using a palette knife, spread the melted chocolate over a clean, uncoated (not non-stick) or enamel baking sheet or clean board to make an approx. 23cm (9inch) square. Gently tap on the work surface to make smooth. Leave in a cool place for a few minutes to set. Line a board with baking parchment.

Use a large bladed sharp Chef's knife for best results, and hold the blade of the knife at a 45˚ angle against the chocolate with both hands, scrape off long, rolled curls of chocolate. The thickness of the curls will depend on the length of the scraping action and the angle the knife blade is held. Transfer the chocolate curls to the board – handle carefully as the chocolate shavings will be fragile. Continue scraping the chocolate until it is all used up. Keep the curls and shavings in a cool place to prevent them from melting, until ready to use.