Martha Collison's rich and decadent chocolate cake

What you need...

• SPONGE
  250g plain flour
  250g Fairtrade caster sugar
  75g Divine cocoa powder
  2 tsp bicarbonate of soda
  ½ tsp salt
  100g Divine 70% Dark Chocolate, chopped
  125g butter, plus extra for greasing
  250ml buttermilk (or 245ml whole milk plus 1 tbsp lemon juice)
  250ml strong-brewed Fairtrade coffee
  2 free range eggs
  WHIPPED CHOCOLATE GANACHE
  150g butter, cubed
  100g Divine Milk Chocolate, chopped
  200g Divine 70% Dark Chocolate, chopped
  2 tbsp Fairtrade golden syrup
  300ml double cream
  TO DECORATE
  100g Divine 70% Dark Chocolate, finely chopped
  75ml double cream
  1 100g Divine Milk Chocolate bar, very finely chopped to aid melting
  3 20cm tins round tins
  2 disposable piping bags, one fitted with a closed-star nozzle

instructions

1. Celebration Cake - 1 Preheat the oven to 180°C/160°C fan/gas 4, grease the cake tins and line them with baking parchment. Place the plain flour, caster sugar, cocoa powder, bicarbonate of soda and salt in a large bowl and stir together.Melt the chocolate and butter together in a heatproof bowl in the microwave or set over a pan of simmering water. When they are fully melted and no lumps remain, whisk in the buttermilk, coffee and eggs.
   
   2 Pour the wet mixture into the dry ingredients, whisking until a smooth, runny batter has formed. Divide the mixture evenly between the three prepared tins, either by counting equal spoonfuls of mixture or by weighing the tins. Bake the three cakes for 25–30 minutes until risen and a skewer inserted comes out clean. Remove from the oven and leave to cool in the tins for 10 minutes, then transfer to a wire rack to cool completely.
   
   3 To make the ganache, place the butter, chocolate and golden syrup in a heatproof bowl over a pan of simmering water. Stir until the mixture is melted and smooth. Remove from the heat and pour in the double cream, then mix until combined. Place in the fridge and chill for 30 minutes until cool but not set firm. Whip the cooled ganache with an electric hand-held whisk for 2–3 minutes until it turns from dark to pale brown. Use a spatula to scrape down the sides of the bowl during the whisking to make sure all the ganache is properly whipped.
   
   4 When the sponges are completely cool, assemble the cake. Put a small blob of the ganache onto a cake stand or serving plate (use a cake turntable if you have one) and place the first layer of sponge on top of it. This will secure the cake and stop it sliding while you decorate it. Spread the first layer of sponge with quarter of the ganache using a palette knife, then top with the second layer of sponge. Repeat the process with the next layer of sponge, then cover the whole cake with a thin layer of ganache. This is called the crumb coat, and stops crumbs spreading into the outer icing. Place the cake in the fridge for 15 minutes for the ganache to set.
   
   5 When the cake has been chilled, completely cover the cake with most of the remaining ganache. Use a large palette knife to create smooth edges by holding it vertically at a 90 degree angle to the cake and running it all the way around. When you’re happy with the appearance, return the cake to the fridge for 30 minutes to firm up. Spoon the remaining whipped ganache into the piping bag fitted with the closed-star nozzle.
   
   6 To make the ganache drip, put the finely chopped dark chocolate in a small heatproof jug. Heat the double cream in a small saucepan until it is steaming, then pour it over the chocolate and stir until all the chocolate has melted. Set to one side to thicken slightly – you want it to be firm enough to hold its shape on the cake but runny enough to drip. Make chocolate curls: melt the milk chocolate and pour the molten chocolate onto a chopping board or marble slab. Leave to set, then run a sharp knife at an angle over the chocolate to form curls.
   
   7 Remove the cake from the fridge. Pipe small swirls of whipped ganache around the top edge of the cake. Spoon the runnier chocolate ganache into the second piping bag, snip off the end and pipe a border around the top edge of the cake, allowing it to run down the sides to create drips the run halfway down the cake. Pipe the remaining runny ganache onto the centre of the cake and spread it gently so that it covers it evenly in one single layer. Allow to firm up for a few minutes, then top with chocolate curls.

This rich and decadent chocolate cake is adapted from Martha Collison’s new cook book ‘Crave’ published by HarperCollins in July 2017 following the success of Martha’s first book ‘Twist’. Made with Divine 70% dark chocolate, this celebration cakes combines dense, fudgy dark chocolate sponge, whipped chocolate ganache and is finished with a chocolate drizzle and chocolate curls for a cake that people dream of. It’s Martha’s most requested birthday cake recipe, perfect for parties! Martha’s new book Crave (published by Harper Collins) is out now.