ine a sieve or colander with cheesecloth and set over a bowl, leaving at least 1/2 inch clearance from the bottom. (Alternatively, use a coffee filter lined with filter paper.) Spoon in yogurt, cover and let drain in the refrigerator for at least 2 hours. Discard whey.
Whip cream in a small bowl until soft peaks form. Add sugar and continue whipping until firm peaks form. Fold in drained yogurt, along with matcha mixture, if using.