For the Bitter Chocolate and Chestnut Cake Base
225g 70% bitter chocolate
125g unsalted butter
5 free range eggs
100g caster sugar
50g ground almonds
125g fresh peeled and roasted chestnuts
100ml dark rum
Preheat the oven to 170°C and line a 28cm x 18cm x 4cm rectangular cake frame with baking parchment. In a small saucepan bring the rum and chestnuts to a simmer; remove from the heat and leave to soak for 10 minutes.
Melt the chocolate and butter in a double boiler. While the chocolate is melting separate the eggs, then whisk the whites with the sugar until they form a soft peak meringue consistency.
Once the chocolate is melted remove from the heat and stir the soaked chestnuts and rum and the egg yolks into the melted chocolate. Fold the whipped egg whites into the mixture.
Spoon the cake mixture into the lined metal frame. Bake the cake for 20-22 minutes in the pre-heated oven. Once cooked, remove the cake from the oven and leave to cool completely. Use the back of a spoon to press the cake down.
For the Bitter Chocolate and Chestnut Mousse
225g 70% bitter chocolate
175g unsweetened chestnut purée
4 free range eggs separated
60ml dark rum
200g double cream
2 leaves of gelatine, dissolved in cold water
50g caster sugar
Weigh the chestnut purée and rum into the bowl of a thermomix, and set the timer for 6 minutes at 80°C, speed 4. Once heated turn the speed dial to 10 for 20 seconds to smoothen the purée, add the chocolate and stir to melt. Add the egg yolks and dissolved gelatine and blend till smooth.
Whip the egg whites with the sugar until they reach the soft peak stage and whip the cream until it forms soft ribbons. Fold the whipped egg whites and cream into the chocolate mixture.
Spread the mousse over the cake, level out and refrigerate until set completely before glazing the cake. This normally takes around six hours.
For the Chocolate Glaze
100ml cold water
100ml double cream
110g caster sugar
40g bitter cocoa powder
2 leaves of gelatine
Soak the gelatine in cold water. In a small saucepan bring the water, cream and sugar to the boil, remove from the heat and add the drained soaked gelatine leaves, stir to dissolve, sift in the cocoa powder and mix well, pass the glaze through a fine sieve and leave to cool to 18°C before pouring the glaze over the set mousse.
For the Candied Chestnuts
250g fresh peeled and roasted chestnuts
200g caster sugar
1tsp unsalted butter
Cut the chestnuts into quarters. Heat a medium non-stick saucepan with the sugar, butter and chestnuts, let the sugar start to dissolve and stir continuously to cause crystallisation while the sugar turns to caramel. Boil until a dark caramel colour, pour the candied crystallised chestnuts out onto a lined baking tray. Leave to set and cool. Chop the candied chestnuts into smaller pieces for serving.
With a warm knife cut the cake into 2cm slices. Place a slice on a plate garnished with chocolate sauce, spoon the candied chestnuts over the top and sprinkle with chocolate cookie dust.