Bring a large pot of salted water to a boil and cook your pasta according to the package directions until al dente. I always taste a strand to make sure it’s perfectly firm. Drain the pasta and set it aside.
Flatten the chicken breasts to even thickness using a meat mallet or the bottom of a pan. Season both sides generously with Cajun seasoning, salt, and pepper. Sauté in a skillet with a bit of oil until golden brown and fully cooked, then slice into strips.
In a deep skillet, melt butter over medium heat and sauté garlic for 30–60 seconds until fragrant. Add diced tomatoes (optional) and cook for 2 minutes. Pour in the cream, sprinkle in remaining Cajun seasoning, and stir in Parmesan. Let the sauce simmer gently.
Add the cooked pasta and sliced chicken to the sauce. Toss gently to coat each piece in creamy goodness. Make sure the pasta absorbs some of the sauce for maximum flavor.
Transfer to a serving dish and top with extra Parmesan and chopped parsley. A slice of crusty bread on the side helps soak up every bit of that luscious sauce.