For the Mousse
330g 70% or higher dark chocolate, in pieces
8 large eggs
100g caster sugar
Generous pinch of sea salt
For the Hazelnut Praline
200g caster sugar
200g Hazelnut, toasted
Mousse
Melt the chocolate slowly in a Bain Marie (bowl of simmering water). Leave to cool.
Beat egg yolks in another bowl with an electric whisk with half of the sugar until thick. Slowly add in the chocolate, mixing all the time with a wooden spoon.
Whisk egg whites to soft peaks, then add the other half of the sugar, slowly. Fold into chocolate mixture, pour into dishes or dish of your choice and refrigerate.
Praline
Scatter the hazelnuts over parchment paper on a work surface. Melt the sugar in a pan on a medium heat, stirring all the time until it becomes caramel. It can burn quite easily so make sure you keep stirring. Pour over hazelnuts and leave to turn solid, then bash up into smaller pieces with a rolling pin.
To serve: sprinkle praline over mousse and serve with a dollop of creme fraiche.