What’s the difference between a chef and a home cook? That’s a question that is obvious on one level but more complicated when you give it more than a passing thought. Over the past few months we’ve had several Los Angeles chefs in our Times Test Kitchen for a new video series we’re calling “Chef That!” As in “chef that ice cream sundae.” Or “chef that grilled cheese sandwich.” The assignment: to demonstrate a dish that is simple enough for a home cook to accomplish with ordinary kitchen equipment but also gives us a glimpse into the priorities and creative forces that shape each chef’s menu — and the way we eat.