01 - Melt the 5.3 oz dark chocolate in a heatproof bowl set over a pan of simmering water using a double boiler method. Stir until completely smooth, then remove from heat and let cool slightly.
02 - In a clean bowl, whisk the egg yolks with 0.7 oz of the sugar until the mixture becomes pale and creamy. Gradually fold in the melted chocolate until fully incorporated.
03 - In a separate bowl, beat the egg whites with salt until soft peaks form. Gradually add the remaining 0.7 oz sugar while continuing to beat until stiff peaks form.
04 - Gently fold the whipped egg whites into the chocolate mixture in three batches, being careful not to deflate the aerated mixture.
05 - In another bowl, whip the 6.8 fl oz chilled heavy cream to soft peaks. Fold gently into the chocolate mixture until just combined.
06 - Divide the mousse evenly among 4 serving glasses or bowls. Refrigerate for at least 2 hours, or until the mousse is completely set.
07 - Whip the 3.4 fl oz heavy cream with 1 tbsp powdered sugar until soft peaks form.
08 - Top each chilled mousse with a dollop of whipped cream. Using a vegetable peeler, create chocolate curls from the remaining 0.7 oz chocolate and sprinkle over the whipped cream. Serve immediately while chilled.