Step 1

Bring a shallow amount of water to a boil in a medium pot. Boiling the pasta in less water creates a very starchy pasta water that is essential to create the sauce for this recipe.

Step 2

Add 2 tablespoons of butter to a large saute pan and melt over medium-low heat.

Step 3

Add in leeks and season with salt and pepper. Cook, stirring occasionally, over medium-low heat until the leeks are very soft, about 10 minutes. Turn the heat all the way down to low while you cook the pasta.

Step 4

Season the boiling water with salt and drop in the pasta. Cook until the pasta is just al dente.

Step 5

Drain pasta (reserving at least 2 mugsful of pasta water) and add the pasta to the pan with the leeks over low heat.

Step 6

Add in the remaining 3 tablespoons of cold butter along with a splash of pasta water. Toss until the butter has melted and the pasta is starting to look creamy.

Step 7

Add in the parmesan in three additions along with splashes of pasta water, tossing until fully melted before adding more cheese. Add as much pasta water as needed to create a creamy, emulsified sauce, and toss, toss, toss!

Step 8

Serve topped with more cheese, very finely grated hazelnuts (I use a microplane), and more black pepper.