Requires: 22cm round cake pan, electric mixer (or hand beater)
Preheat oven to 180°C conventional oven (350° Fahrenheit/Gas 4). Grease a 22cm round cake pan by lightly buttering the base and sides with margarine or butter. Line the base with baking paper, then lightly butter over the baking paper. Add a heaped tablespoon of 00 flour, then turn and shake the tin to coat the butter in flour on the base and sides of the cake pan.
Place the dark chocolate in a heatproof bowl set over a pan of simmering water (don’t let bowl touch the water). Cook, stirring using a metal spoon, until the chocolate has melted to a smooth consistency. Remove the bowl with melted chocolate from the heat and allow to cool.
Using an electric mixer or hand beater, beat the egg whites with a pinch of salt until stiff peaks form. With the mixer (or hand beater) running, add the egg yolks, one at a time. Add the sugar, one tablespoon at a time, beating well after each addition.
Use a wooden spoon to stir in half of the flour and unsweetened cocoa powder (cacao magro), one tablespoon at a time. You want to see air bubbles rise to the surface of the cake mixture before adding additional tablespoons of flour. Stir in the milk, then add the remaining flour and cocao once tablespoon at a time. Stir in the butter until well combined. Stir the sifted baking powder, then the melted chocolate into the cake mixture.
Note: 00 is a powder-fine Italian type of flour. It is made from soft wheat varieties, and is frequently used in Italian desserts and pastas. 00 flour is available in most supermarkets, Italian food stores and gourmet delicatessens.
Pour the cake mixture into the prepared cake pan. Bake for 1 hour 10 minutes or until a skewer inserted in centre comes out clean. Allow to cool in the cake pan for 10 minutes, then transfer to a wire rack to cool completely.
Meanwhile to make the Cream filling, place the thickened cream in a large bowl. Add the sifted icing sugar and vanilla bean seeds (or vanilla bean paste). Use an electric mixer or hand beater to beat until stiff peaks form. Beat in the mascarpone, one heaped tablespoon at a time until well combined. Refrigerate until ready to use.
To make the Chocolate ganache topping, place the dark chocolate in a heatproof bowl set over a pan of simmering water (don’t let bowl touch the water). Cook, stirring using a metal spoon, until the chocolate has melted to a smooth consistency. Remove from the heat and stir the thickened cream into the melted chocolate. Remove the bowl with melted chocolate from the heat and set aside to cool slightly.
Once the Chocolate Sponge Cake has cooled, use a serrated knife to cut the cake in half horizontally. You may also wish to cut off the peak from the top of the cake so it lies flat and even. Set aside the top half. Transfer the bottom half of the Chocolate Sponge Cake onto a serving plate. Spoon the Cream filling over the bottom half of the cake. Place the remaining cake on top, pressing down gently to secure it. Pour the Chocolate ganache topping over the top and sides of the cake. Allow the chocolate ganache to set for 30 minutes in the fridge before decorating with chocolate Easter eggs on top – buon appetito.