Give a sweet thank-you with individual desserts (cakes, even pies) in a jar. For cheesecake, fill jars about three-quarters full with cheesecake mixture. Bake uncovered in a large baking dish, with enough hot water to reach three-quarters of the way up the jars, until set, 25 to 35 minutes. Let cool and top with preserves, if desired. Refrigerate for at least 2 hours and up to 3 days.