Preheat the oven to 180°C / 350°F on conventional bake.

Grease and line two 20cm round shallow sandwich tins with baking paper. Grease paper with a little more butter.

Sift together the flours, cocoa, baking powder and salt three times.

Combine the eggs, vanilla essence, coffee powder in a large mixing bowl. Beat on high until soft cream for about 10 minutes.
Gradually beat in the sugar a tablespoon at a time until dissolved for another 10 minutes until ribbons of butter hold for 10 seconds on top of the batter.

Fold in the sifted flour mix until just combined. Place immediately into the oven and bake for 25 minutes or until the cakes are springy to touch and come away from the sides of the tins.

Allow to cool, for 5-10 minutes in the tin then turn onto wire racks. Remove the baking paper.

To make the filling, combine the cream and both kinds of chocolate in a saucepan. Place over a low to medium heat and bring to the boil, stirring to melt the chocolate and prevent scorching.

As soon as the mixture boils, remove it from the heat. Cool, stirring once in a while, until the mixture starts to thicken and set. When cool, place in the bowl of an electric mixer. Add the rum if using and whisk at high speed for 4 to 5 minutes. The filling will lighten in colour and approximately double in volume. Use immediately, the filling quickly becomes hard and un spreadable.
When cakes are cool, spread with chocolate filling on one half and top with fresh raspberries. Sandwich the two layers together and the sprinkle whole cake with a little icing sugar and cocoa powder mixed together.

For expert sponge baking techniques look at our Perfect Sponge Cake feature.