Start by bringing a large pot of salted water to a boil. Add the rotini and cook according to package instructions until al dente (usually about 8-10 minutes).

Reserve about a cup of pasta water before draining; it can help adjust the sauce's thickness later.

While the pasta is cooking, cut the chicken breast into bite-sized pieces and season generously with salt, pepper, and Cajun seasoning.

In a large skillet, melt 2 tablespoons of butter over medium-high heat. Add the seasoned chicken and cook until golden and cooked through, about 6-8 minutes.

Once the chicken is cooked, add the minced garlic to the skillet and sauté for 1-2 minutes, being careful not to burn it.

Remove the cooked chicken and garlic from the skillet. Add the remaining butter and heavy cream to the skillet, mixing well. Let it simmer for about 3 minutes.

Add the cooked rotini and chicken back into the skillet, tossing everything together to combine. If the sauce seems too thick, add reserved pasta water gradually until you reach your desired consistency.

Stir in the grated Parmesan cheese until melted and fully incorporated. Taste and adjust seasoning with more salt, pepper, or Cajun seasoning, if desired.

Serve hot, garnished with fresh parsley for a pop of color.