Line 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 1 cup nonfat or low-fat vanilla yogurt, cover and let drain in the refrigerator for 1 hour. Discard whey. Whip 1/4 cup whipping cream in a small bowl until soft peaks form. Add 2 1/2 teaspoons confectioners’ sugar, if desired, and continue whipping until firm peaks form. Fold in the drained yogurt.