Step 1

Combine 2 quarts (1.8 liters) water and the kosher salt in a pot and bring to a boil. Add the macaroni and return to a boil. Cook the macaroni until barely al dente, about 5 minutes from when it returns to a boil.

Step 2

Drain the macaroni in a colander and shake it dry. Dump the macaroni on a rimmed baking sheet, drizzle with the oil, and gently toss until it’s evenly coated to keep the macaroni from sticking to one another. Let cool completely. You should have about 3 cups.

Step 3

Set a rack in the oven about 4 inches (10 cm) from the broiler and preheat the broiler.

Step 4

Toss the grana padano, Jarlsberg, and white Cheddar in a large bowl until well combined. Then separate the mixed cheeses into two piles, one slightly larger than the other. [Editor’s Note: Ideally you want the smaller pile to be 40% of the whole and the larger pile to be 60%.]

Step 5

In a large, deep saucepan over medium-high heat, bring the cream and sea salt, if using, to a boil. Let simmer for about 2 minutes. The cream will foam up and then subside into a simmer. Add the macaroni and continue to cook, stirring occasionally, for about 90 seconds. The cream will start to thicken just slightly and coat the noodles.

Step 6

Start adding the 40% pile of cheese in small handfuls, stirring and waiting for the first handful of cheese to melt and incorporate into the sauce before adding the next handful. Transfer the contents of the pan to a 2 1/2-quart (2.4 liter) ovenproof skillet or baking dish. The mixture will be runny but that’s okay. Mound the reserved cheese on top of the macaroni and place the dish on a rimmed baking sheet to catch any drips.☞TESTER TIP: The mac and cheese mixture will be very runny when you pour the cream and pasta into the baking dish. Don't worry. It'll come out just fine.

Step 7

Slide the baking sheet into the oven and broil, rotating the skillet or dish often, until the cheese melts and caramelizes into a golden brown crust, 3 to 5 minutes. Watch it carefully as every broiler is different and your cheese can go from not-quite-golden-brown to charred-as-charcoal in a matter of seconds.

Step 8

Remove the macaroni au gratin from the oven and let it rest for 5 minutes. Devour immediately.