Tie yogurt in the muslin cloth and hang overnight to drain out the whey. This should preferably be hung in the refrigerator.
Transfer the hung yogurt into a mixing bowl and add powdered sugar. Mix well till sugar is totally dissolved.
Melt chocolate in a double boiler or in a microwave oven. Whisk till it is smooth and slightly cooled. Add in fresh cream and continue to whisk till well blended.
Pour this mixture into the yogurt mixture in circles to get a marbled effect. Do not mix. Keep it in the refrigerator to chill. Served chilled sprinkled with toasted almond slivers.