This is not your traditional Italian ricotta cheese. Ricotta is Italian for "twice-cooked" or "to cook again" and is usually made from the whey you get from making another cheese, such as mozzarella or a hard cheese. For proper ricotta, whey is heated, with or without additional vinegar, and the new cheese is strained. Whole milk is never used.
This recipe is a variation on my basic farmer cheese, with added cream for a smoother, creamier consistency that works well for filling pasta shells or topping pancakes. Use really fresh milk for the best flavor and longevity.
Pour the milk, cream, and salt into a 3-quart stainless steel saucepan, and heat the milk to 190° F (88° C), stirring occasionally to keep it from scorching on the bottom. Remove from the heat and add the lemon juice, slowly stirring once or twice. Let the pot sit for 5 minutes. The milk will separate and form curds and whey.
Line a sieve with cheesecloth and place it over a large bowl. Pour the curds and whey into the sieve, and let strain for at least 1 hour.
Eat right away or transfer to an airtight container and refrigerate until ready to use. (Fresh ricotta will keep in the fridge for one week.)