Pour cream into a double boiler fitted with a thermometer. Heat cream until the thermometer reads 185 degrees F (85 degrees C), about 10 minutes. Add tartaric acid; cook, stirring constantly, until cream thickens and curds start to form, about 5 minutes
Scoop curds into a sieve lined with several layers of cheesecloth using a slotted spoon. Fold the edges of the cheesecloth over the curds and let drain over a bowl at room temperature, about 1 hour.
