How to Make It
Cook pasta according to package directions. Drain and set aside.
Add oil to a large skillet over medium-high; tilt to coat skillet. Toss together shrimp and Cajun seasoning in a medium bowl to coat. Add shrimp to skillet; cook until opaque, about 2 minutes per side. Transfer shrimp to a plate.
Add onion, celery, and garlic to skillet; cook, stirring often, until onion is tender, about 3 minutes. Add chicken stock; stir to loosen browned bits from bottom of skillet. Stir in heavy cream, Parmesan, pepper, salt, and cayenne. Cook, stirring often, until thickened, 4 to 5 minutes. Add cooked pasta; toss to coat. Top with shrimp; sprinkle with scallions.