A good caramel apple should be about two things: One, true caramel flavor (there are a lot of shortcut versions that are basically milk candy) and two, actually eating well (not shattering, not ripping fillings out). This is the old pastry chef approach that gives both: slightly higher fat caramel cooked only to about 245 to 247°F so it sets but doesn’t go to hard crack. It holds its glossy look, it never gets grainy, and you can bite it cleanly.