Set until it coagulates, usually about an hour. Heat slowly by the double boiler method until the temperature reaches about 110 degrees F. Hold at this temperature for 30 minutes and stir often to prevent matting. When the curds are firm, place into a cheesecloth-lined colander and let drain for 20 minutes. Lift the curds in the cheesecloth and dip into a pot of cold water. Drain until the curd stops dripping.
Place curds in a bowl and add salt and cream if desired.
Allow the milk to set to ripen for one hour. Keep the milk warm at 88 degrees F during this time. This can easily be done by placing the milk in a sink full of warm or hot water. Cool or hot water can be added as needed. After one hour, mix the rennet in cool water and stir into the milk for 30 seconds.