Chocolate sponge

1. Heat oven to 210C.
2. Make a sabayon by whisking the eggs and sugar in a metal bowl over a pot of simmering water until light and fluffy.
3. Remove from the heat and whisk on high speed until the mix has tripled in size. Sift in the flour and cocoa and fold through, then carefully fold through the melted butter.
4. Spread evenly to 4mm thin on a baking tray lined with baking paper. Cook for 4 minutes then allow to cool.
5. Cut a piece of the sponge to fit the base of a loose bottom cake tin — I sometimes use a square plastic container, you can even try making individual cakes.
6. To help remove the truffle cake once it has set, line your tin or container with a piece of plastic wrap.
7. Make a simple liqueur syrup by boiling together 4 Tbsp each of water and sugar until dissolved. When cool add 1 Tbsp Kahlua.
8. Pour a little of the liqueur syrup over the sponge in the container to moisten it.

Chocolate truffle

1. Melt the chocolate in a metal bowl over a pot of simmering water.
2. Make a sabayon by whisking the egg yolk, eggs and sugar in a metal bowl over a pot of simmering water until light and fluffy. Remove from the heat.
3. Squeeze excess water from gelatine then melt in a saucepan over a medium heat. Add the gelatine to the sabayon and whisk on high speed until the mix has tripled in size.
4. Gently fold the melted chocolate into the sabayon a little at a time, then fold in the cream, mixing thoroughly after each addition — two spoonfuls to start, then the remainder, in thirds.
5. Pour the truffle mix on to the sponge, cover with plastic wrap then place in the fridge overnight.
6. Use a long sharp knife dipped in hot water to cut truffle cake into neat sharp rectangles. Lightly dust with Dutch cocoa and serve with a berry coulis and raspberries to garnish.

Geoff recommends

• Gelatine leaves can be purchased from some supermarkets and specialty food shops.
• For an alcohol-free cake, omit the kahlua.
• Extra sponge can be carefully wrapped and frozen and used for a second truffle cake.
• Here is a recipe for berry coulis.