A LOT of R&D has gone into Milk Truck’s grilled cheese. It is the flattest I’ve seen, a model of concision, a novella to other grilled cheeses’ “Infinite Jest.”

The bread (levain pullman from Balthazar) is crenulated and crisp, the cheese (aged Gruyère from Wisconsin) tangy. But the pivotal ingredient is the cultured butter, made from fermented cream. It is to butter what butter is to margarine: richer, fuller, more emphatic. Slathered on all sides, it has colonized the bread’s every pore.

Sure, you could make this at home, provided you could find the proper ingredients, had access to a panini press (a kettle or flatiron won’t do) and tuned the heat precisely, so the cheese didn’t go past gooey into glop.

Why not just pay $5.75 for the version executed with military precision, if not always speed, by MILK TRUCK, various locations, (917) 520-7415, milktruckgrilledcheese.com? It was the best I tried in a recent tour of artisanal grilled-cheese shops, a culinary subgenre that has boomed in the last year.