This cake recipe is much less complicated than it looks and the result is awesome, so go for it.
For the sponge
120g ground almonds
150g icing sugar, sifted
4 egg yolks
25g plain flour, sifted
25g unsweetened cocoa powder, sifted
5 egg whites
60g castor sugar
For the ganache
300g dark chocolate
300ml whipping cream
For the rum syrup
100g castor sugar
2 tsp rum
1. Preheat oven to 180°C. Line a 30cm by 38cm baking tray or Swiss roll tin with baking paper.
2. Combine the ground almonds, icing sugar, whole eggs and egg yolks and beat for 5 minutes until light and creamy. Fold in the sifted flour and cocoa powder. Whisk the egg whites in a large bowl, gradually adding the sugar until the egg whites are smooth and shiny and stiff peaks form. Fold the egg whites into the chocolate mixture one third at a time. Pour the batter into the prepared tin and bake for 12 minutes.
3. For the chocolate ganache, finely chop the chocolate and place in a bowl. Heat the cream in a saucepan until it's simmering, pour it over the chocolate, then whisk until smooth. Set aside to cool and thicken.
4. For the rum syrup, bring the sugar and 100ml of water to a boil, remove from the heat and allow to cool to room temperature before adding the rum.
5. Trim sponge and cut across into three pieces, each about 12cm by 28cm. Brush the first piece with rum syrup and spread with a thin layer of ganache; place the second sponge piece on top and add some syrup and ganache. Top with the remaining sponge and add more syrup and ganache, setting the last of the ganache aside for the final decoration. Refrigerate for 30 minutes.
6. Spread all the remaining ganache over the top of the cake.