Put both milks, the cream, and the lemon juice into a large nonreactive saucepan or stew pot. Turn the heat to low and bring to 194 degrees using a candy thermometer, making sure it does not touch the bottom or sides of the saucepan or pot. This will take about 2 hours. Line strainer or small colander with cheese cloth. When curds form on the surface of the liquid, remove them with a skimmer or slotted spoon and transfer to the strainer. Increase the heat to medium and after 8 minutes, skim some more, until all the curds are removed and only milky liquid remains. Leave the curds to drain for 1 hour, then transfer them to container and refrigerate. Fresh homemade ricotta will stay fresh for about 4 days in the refrigerator and may be used in recipes.