Cook the rotini pasta according to package instructions. Drain and set aside.

While the pasta is cooking, heat a drizzle of olive oil in a large skillet over medium-high heat.

Season both sides of the chicken breast with 1 tablespoon of Cajun seasoning. Add the chicken to the skillet and cook for about 3 minutes on each side, or until the chicken reaches an internal temperature of 165°F (75°C). Remove the chicken from the skillet and set aside.

In the same skillet, reduce the heat to medium. Add the unsalted butter and let it melt. Add the minced garlic and minced onion, sauté for about 30 seconds until fragrant.

Stir in the tomato sauce and cook for a few minutes, allowing the flavors to meld.

Pour in the heavy cream and chicken broth. Bring to a simmer and cook, stirring occasionally, until the sauce starts to thicken.

Add the remaining Cajun seasoning and lemon juice to the sauce. Stir in the grated Parmesan cheese until melted and well combined.

If desired, set aside a portion of the sauce to drizzle over the chicken later.

Add the cooked pasta and chopped fresh parsley to the skillet with the sauce. Toss everything together until the pasta is well coated with the sauce. Season with salt and black pepper to taste.

Slice the cooked chicken breast and serve it on top of the creamy Cajun pasta. Drizzle with the reserved sauce if desired. Garnish with additional parsley.

Serve immediately and enjoy your creamy Cajun chicken pasta!