Line a colander with a layer of cheesecloth and set it over a large bowl.
Stir the milk, cream, and salt together in a pot. Heat over medium heat, stirring now and then, until the mixture reaches 190°F — steaming hot and just about to simmer.
Take the pot off the heat and stir in the lemon juice. Let it stand a few minutes while the milk separates into soft white curds and thin, watery whey.
Pour the curds and whey into the prepared colander and let them drain for at least 1 hour, until the ricotta is thick and spreadable.
Transfer to a container, cover, and refrigerate.
For a softer, wetter ricotta, drain only 10–20 minutes. Serve on cucumber rounds, apple slices, or gluten-free crackers, or by the spoonful with honey.