I mentioned in another thread that I’ve tried two Cook Out locations and found the food mediocre at best. The 40,000 shake flavors is their deal.
Their shakes are good because they use (or at least did when I was there) two different types of cream mix in their ice cream machines. The combination is really good. That and they use actual ingredients. Like if you're getting a cheesecake shake, the cup starts with an actual piece of cheesecake in it, then they put the ice cream mixture.
They use good ingredients, but it does have to be cooked decently. There are no propietary secrets. Slap a burger patty on a grill, cook it, then transfer it to a flat grill to keep it warm. Put it back on the grill for a last second char IIRC. Basic stuff, really.
Fun fact - people rave about their cajun fries. Their just waffle fries with seasoned salt instead of regular salt or any type of actual "cajun" seasoning. lol