Begin by heating 1/2 cup of heavy whipping cream in a small saucepan over medium heat until it just begins to simmer. Remove from heat and stir in chopped white chocolate until smooth. Mix in 1-2 teaspoons of matcha, then cool slightly.

In a large bowl, combine remaining heavy cream, 2 tablespoons of sugar, and 1 teaspoon of vanilla extract. Whip on medium until soft peaks form, about 3-5 minutes.

In a separate bowl, beat 2 egg whites with a pinch of salt on medium-high until stiff peaks form, about 3-4 minutes.

Gently fold the chocolate mixture into the whipped cream, then carefully fold in the whipped egg whites. Continue until no streaks remain and the mixture is light green.

Spoon the mousse into serving dishes, cover, and refrigerate for at least 2 hours.

Garnish with matcha powder or white chocolate shavings before serving. Enjoy!