Every family needs a good chocolate cake recipe for special occasions, and this is mine, inspired by the Icebreaker chocolate and mint bars I enjoyed as a child. It has no flour in it, using beaten egg whites to give it a lift instead, so it may sink a little after coming out of the oven. Don’t worry, no one will notice once you’ve added the topping.
Preheat the oven to 180°C/Gas 4. Lightly grease a baking tray with a little groundnut oil. Lightly grease a 23cm springform cake tin and line the base with baking paper.
2. Pour 100g of the caster sugar into a large frying pan and place it over a medium heat, shaking the pan occasionally, but not stirring, to ensure it melts evenly. Once it has turned a deep golden colour, scatter it with the mint leaves and tip on to the prepared tray. Set aside to cool. When cold and firm, break half the caramel into pieces and place in a bowl. Using the end of a rolling pin, crush them into very small pieces and set aside. Break the remaining caramel into small shards and reserve for decoration.
3. Melt the chocolate in a bowl that fits snugly over a pan of gently simmering water. (The bowl must not actually touch the water.) Add the butter and stir until melted. Set aside to cool slightly.
4. Beat 2 whole eggs and 3 egg yolks with 75g of the caster sugar until thick, light and fluffy. Fold in the chocolate mixture, then fold in the crushed caramel.
5. In another bowl, whisk the egg whites into soft peaks, then add the remaining 100g caster sugar a little at a time until it is all incorporated. The mixture should be in stiff, glossy peaks that hold their shape.
6. Fold a spoonful of the whites into the chocolate mixture, then carefully fold in the rest of them. Spoon into the prepared tin and bake for 35–40 minutes, until the cake has risen and the centre is no longer wobbly. Set aside to cool in the tin. Don’t worry if the middle sinks a little – this often happens with flourless cakes. When cold, transfer the cake to a serving plate.
7. To make the topping, put the cream into a bowl, sift the icing sugar over it and add the peppermint extract. Whisk together until the cream begins to thicken and just holds its shape – take care not to overwhip.
8. Spoon the topping over the surface of the cake, leaving a narrow border around the edge to make for neater cutting.
9. Scatter the reserved caramel shards on top and serve.