For the praline, line a baking tray with greaseproof paper. Heat a frying pan over a high heat until hot. Add the sugar and cook until the sugar has completely melted and is sticky and golden-brown.
Add the chopped hazelnuts and stir until they are coated in the sugar mixture, then pour the mixture onto the prepared baking tray. Set aside until the mixture has hardened.
When the praline mixture has hardened, cover with a sheet of cling film and break into small pieces using a toffee hammer or rolling pin. Set aside.
For the dark chocolate mousse, bring a pan of water to a simmer. Suspend a heatproof bowl over the water (do not allow the base of the bowl to touch the water). Add the dark chocolate and warm water to the bowl and stir until smooth and glossy and completely melted. Remove from the heat and set aside to cool slightly.
Suspend a separate, clean bowl over the pan of simmering water, add the egg yolks and sugar and whisk continuously for 3-4 minutes, or until the mixture is pale and has thickened. Remove from the heat and set aside to cool slightly.
Place half of the cream and the softened gelatine into a separate pan and heat gently over a medium heat, stirring until the gelatine has dissolved.
Add the cream mixture to the melted chocolate and whisk until well combined.
Add the egg yolk and sugar mixture and whisk again until well combined.
In a separate bowl, whip the remaining cream until soft peaks form when the whisk is removed. Fold the whipped cream into the chocolate mixture.
Line a 1kg/2lb loaf tin with cling film. Carefully pour the dark chocolate mixture into the loaf tin and tap the sides gently to get rid of any air bubbles. Chill the fridge for at least 30 minutes, or until just set.
For the white chocolate mousse, suspend a clean heatproof bowl over the pan of simmering water (do not allow the base of the bowl to touch the water). Add the white chocolate to the bowl and stir until smooth and glossy and completely melted. Remove from the heat and set aside to cool slightly.
Suspend a separate, clean bowl over the pan of simmering water, add the egg yolks and sugar and whisk continuously for 3-4 minutes, or until the mixture is pale and has thickened. Remove from the heat and set aside to cool slightly.
Place half of the cream and the softened gelatine into a pan and heat gently over a medium heat, stirring until the gelatine has dissolved.
Add the cream mixture to the melted chocolate and whisk until well combined.
Add the egg yolk and sugar mixture and whisk again until well combined.
In a separate bowl, whip the remaining cream until soft peaks form when the whisk is removed. Fold the whipped cream into the chocolate mixture.
When the dark chocolate mousse has just set, carefully pour the white chocolate mixture into the loaf tin, on top of the dark chocolate mousse, then tap the sides gently to get rid of any air bubbles. Chill the fridge for at least two hours, or until completely set.
For the strawberry and ginger compote, blend 250g/9oz of the strawberries, all of the stem ginger and the icing sugar in a food processor to a purée.
Pass the mixture through a fine sieve, collecting the sieved liquid in a bowl. Reserve the liquid.
Heat the butter in a frying pan over a medium heat. When the butter is foaming, add the remaining strawberries and fry for 1-2 minutes, or until just softened.
To serve, spoon a little of the strawberry and ginger compote into the centre of each of eight serving plates. Cut the dark and white chocolate terrine into eight slices using a hot knife. Place one slice into the centre of each plate. Garnish each plate with a few of the remaining strawberry halves. Sprinkle over the praline pieces.
