Cook the penne pasta according to package directions, drain, and set aside.
Toss the chicken strips with 1 tablespoon Cajun seasoning until evenly coated.
Heat olive oil in a large skillet over medium-high heat and cook the chicken for 5 to 6 minutes per side until blackened and cooked to 165°F / 74°C, then remove and set aside.
In the same skillet, add garlic and cook for 30 seconds, then add heavy cream, diced tomatoes, remaining Cajun seasoning, and Parmesan, stirring until the sauce thickens for 3 to 4 minutes.
Add the cooked pasta and chicken to the skillet and toss until everything is coated in the sauce.
Serve immediately with extra Parmesan on top if desired.