Method

1. Prepare a 20cm cake tin by lining with baking paper.

2. To make the praline, line a baking tray with baking paper. Toast the hazelnuts in a dry saucepan until they are golden. Remove from the pan and set aside.

3. Put the sugar and water in the pan and heat gently until the sugar dissolves. Increase the heat to high (avoid the temptation to stir it). When the caramel begins to turn a dark golden brown, remove from the heat and quickly stir in the hazelnuts. Pour immediately on to the lined baking tray and spread out evenly. Leave to cool. Once the caramel is cool and hard, blitz to a fine powder in a food processor.

4. Make the biscuit base by melting the butter and chocolate together in a medium heatproof bowl over a pan of just-simmering water.Add the crushed biscuits and stir to combine. Press intothe prepared cake tin to form a crust and place in the freezer.

5. Place the eggs, extra yolks, vanilla and sugar in a large heatproof bowl. Place the bowl over a saucepan of simmering water. You want the bowl to just be resting over the saucepan – don't let the bowl touch the water. Whisk the mixture continuously for six to eight minutes or until it becomes thick and pale. If you have a hand held electric whisk, opt for that. When the whisk leaves a ribbony trail in the mixture when you lift it up, it is ready. Remove from the heat and allow mixture to cool slightly.

6. Whip the cream in a medium bowl until stiff peaks form. Gently fold through the cooled egg mixture until well combined.

7. Stir two-thirds of the praline into the ice-cream  mixture and pour into the cake tin over the crumb base. Scatter the top with the remaining praline and leave to chill until frozen (at least four hours).

8. Serve in slices.