In a microwave-safe bowl, melt the chopped white chocolate in 30-second intervals, stirring between each, until smooth. Allow to cool slightly.
In a large mixing bowl, whip 1 cup of heavy cream and the vanilla extract until soft peaks form. Set aside.
In another bowl, beat the egg whites with a pinch of salt until soft peaks form. Gradually add the granulated sugar and continue beating until stiff peaks form.
Gently fold the melted white chocolate into the whipped cream until combined.
Carefully fold in the beaten egg whites, being cautious not to deflate the mixture.
Spoon the mousse into individual serving dishes or a large bowl and refrigerate for at least 2 hours, or until set.
Serve chilled, garnished with additional whipped cream or white chocolate shavings if desired.