Cook pasta in well-salted water until al dente. Reserve ½ cup pasta water, then drain.
Toss chicken with Cajun seasoning.
Heat olive oil in a large skillet over medium-high heat. Cook chicken until golden and cooked through. Remove and set aside.
In the same skillet, add garlic and cook for 20–30 seconds until fragrant.
Pour in heavy cream and bring to a gentle simmer, scraping up any browned bits.
Reduce heat to low and stir in Parmesan until melted and smooth.
Return chicken to the skillet. Add cooked pasta and toss to coat.
Add pasta water as needed to loosen the sauce.
Taste, adjust seasoning, garnish, and serve hot.