Step 1

Bring a large pot of heavily salted water to a boil. Meanwhile, finely chop 1 medium shallot or 1/4 medium yellow onion, and 4 garlic cloves (about 1 tablespoon); place both in a small bowl. Pick the leaves from 1/2 medium bunch fresh parsley and finely chop until you have 1/2 cup. Shred 2 ounces Parmesan on the smaller holes of the box grater (about 1/2 cup).

Step 2

Cut 6 to 7 ounces andouille sausage crosswise into 1/3-inch thick rounds. Peel and devein 1 pound raw jumbo shrimp if needed. Pat the shrimp dry and place in a medium bowl. Add 1 tablespoon Cajun seasoning and toss to evenly coat.

Step 3

Add 8 ounces dried fettuccine or penne pasta to the boiling water and cook according to package instructions until al dente, 8 to 12 minutes. Reserve 1 cup of the pasta water. Drain the pasta.

Step 4

While the pasta is cooking, heat 1 tablespoon of the neutral oil in a large high-sided skillet over medium-high heat until shimmering. Add the sausage and cook, stirring occasionally, until some of the fat renders out and it’s golden-brown on the outside, about 5 minutes. Using a slotted spoon, transfer to a large bowl.

Step 5

Reduce the heat to medium. Add the shrimp in a single layer and cook until pink and just cooked through, 2 to 3 minutes per side. Transfer the shrimp to the bowl with the sausage.

Step 6

Add the remaining 1 tablespoon neutral oil and shallot and garlic to the skillet. Cook, stirring occasionally, until the shallots are translucent and garlic is golden-brown, about 2 minutes.

Step 7

Add the Parmesan, 1 1/2 cups heavy cream, 1/2 cup of the pasta water, and 1/2 of the parsley. Stir to combine and bring to a simmer. Return the shrimp, sausage, and any accumulated juices to the skillet. Add the pasta and toss until coated and warmed through and the sauce has thickened slightly, about 2 minutes.

Step 8

Remove the skillet from the heat. If the sauce is too thick, toss in more of the reserved pasta water as needed. Taste and season with kosher salt as needed: If the Cajun seasoning was salt-free, start with 1 1/2 teaspoons, then taste and add more as needed. Garnish with the remaining parsley and more Parmesan cheese.