Step 1

In a small pot over medium-low heat, cook the oil and garlic, stirring occasionally, for 2 to 3 minutes, until the garlic just begins to caramelize. Remove the pot from the heat.

Step 2

Meanwhile, set a large pot of water over high heat. When the water is boiling, add the peas and cook for 2 minutes, then use a slotted spoon to transfer to a blender (we’ll use that water to cook the pasta in just a bit).

Step 3

To the blender, add the garlic and oil, mint, water, lemon juice, and salt; season with black pepper. Blend on high speed until a smooth purée forms. Taste and adjust with salt and lemon juice as needed.

Step 4

Do Ahead: The purée, without the lemon juice, can be made 3 days ahead. Store in an airtight container in the refrigerator. Add the lemon juice the day you're going to serve.

Step 5

To prepare the leeks, remove the tough, dark green outer layers. Halve each leek lengthwise, keeping the root end intact. Rinse the leeks under cold running water, carefully removing all of the dirt and grit from the layers. Slice into half-moons about ½ inch wide; discard the root.

Step 6

Bring the water used to cook the peas back to a boil. Meanwhile, in a large skillet over medium heat, cook the leeks, oil, chili flakes, and ¼ teaspoon of the salt, stirring occasionally, for 6 to 8 minutes, until the leeks are soft and just beginning to caramelize.

Step 7

When the water is rapidly boiling, season with salt until the water tastes pleasantly salty, then cook the fusilli for 1 minute less than the package directions. Drain, reserving ½ cup of the pasta cooking liquid.

Step 8

Add the pasta and the reserved pasta cooking liquid to the skillet with the leeks and toss to combine. (If you feel like your skillet isn’t big enough for all that pasta, just transfer back to the pasta pot.)

Step 9

Add the pea purée and ⅓ cup of the mint to the pasta and heat over medium. Stir until the pasta is fully coated with the sauce, then add 1 cup of the Pecorino. Stir until the sauce is warm and clings to the fusilli. Taste and adjust the seasonings.

Step 10

Divide the pasta among plates or bowls. Garnish with mint and a dusting of Pecorino.