1. Preheat the oven to 230°C/450°F/Gas 8. Line a terrine 30 x 7.5 cm (12 x 3 in) with cling film. Set the freezer to its coldest. 2. To start the praline base of the nougat, warm the hazelnuts in the preheated oven for about 3-4 minutes, or until golden brown. Chop roughly. 3. Heat 150 g (5 oz) of the sugar in a heavy based pan to melt and make a caramel 4. Stir in the warm toasted hazelnuts, and pour on to a cold oiled tray. Leave to coal and set. 5. When cold crush into small pieces, using a rolling pin. 6. Whip the egg whites and the remaining sugar together to make a stiff meringue. 7. Whip the cream to stiff peaks, then fold together gently with the meringue and crushed praline until mixed. 8. Fill the terrine to the fop with the mixture, and place in the freezer until hard, at least 24 hours. 9. To serve, remove the terrine from the freezer, and from the dish. Cut into slices and serve