Cook the rigatoni in a large pot of salted boiling water according to package directions until al dente; drain and keep warm.
Heat the olive oil in a large sauté pan over medium heat.
Season the cubed chicken thighs with kosher salt and ground black pepper, then add to the hot pan and cook until cooked through and browned, about 3–4 minutes per side depending on size.
Add the minced garlic to the pan and cook until fragrant, about 1 minute.
Add the cream cheese pieces to the pan and stir until melted and smooth.
Stir in the peas, marinara sauce, and shredded Parmesan, and simmer gently until the cheese is melted and the sauce is smooth.
Pour in the heavy cream, stir to combine, bring back to a low simmer, then remove the pan from the heat.
Toss the drained rigatoni with the sauce until evenly coated.
Serve topped with extra shredded Parmesan and chopped fresh basil if desired.
