Step 1

Add 3 big handfuls of kosher salt to a large pot of water and bring to a boil. (You're probably tired of us saying it all the time, but, yeah: Salting your pasta water generously is the key to well-seasoned pasta, period.) Drop 1 lb. small shells into boiling water and give them a good stir to be sure nothing sticks. Set a timer according to package directions for al dente.

Step 2

Cut 1 stick chilled unsalted butter into 8 pieces.

Step 3

While pasta is cooking, heat 2 Tbsp. butter and 2 tsp. freshly ground pepper in a large heavy pot or Dutch oven over medium, stirring occasionally, until butter is melted and foaming, but not browned, and pepper is fragrant, about 1 minute.

Step 4

Add 1 cup whole milk to butter to stop it from browning and bring to a simmer. Whisk remaining 6 Tbsp. butter into milk mixture 1 Tbsp. at a time, allowing each to fully melt before adding the next. (Doing this gradually is important—it helps to emulsify your sauce.) You may need to adjust your heat occasionally to maintain a simmer. If pasta still needs a few more minutes to cook, turn off heat under your sauce, cover pot, and keep warm.

Step 5

Scoop up 2 cups pasta cooking liquid with a large glass measuring cup. You're probably not going to use all of the pasta water in your sauce, but it's better to have more than you'll need.

Step 6

Drain pasta and add to pot with milk mixture. Return to medium heat and cook, tossing with a wooden spoon to evenly coat all shells, about 30 seconds.

Step 7

Add about one-third of grated Parmesan, stirring pasta vigorously with wooden spoon to melt. Add about ½ cup reserved pasta water and continue to stir until combined. Repeat this process 2 more times with remaining Parmesan. You may not need all of the pasta water, so add ½ cup at a time until pasta is very creamy and well coated. It’s always good to err on the side of looser (with a little extra pasta water) because the sauce will thicken as it cools. Give it a taste and add more salt, if needed.

Step 8

Divide pasta between bowls—or just heap it into one big bowl for yourself, no judgie—and serve right away.