ine a sieve with cheesecloth and set over a bowl, leaving at least 1/2-inch clearance from the bottom. Spoon in yogurt. Cover and let drain in the refrigerator for 1 1/2 hours.
Discard whey. Whip cream into soft peaks in a chilled bowl with chilled beaters. Push cream to one side; add drained yogurt and fold in with a rubber spatula. Fold in candied ginger.