Cook the Pasta: Bring a large pot of salted water to a rolling boil. Add the rotini and cook until al dente, about 8–10 minutes. Reserve about ½ cup of pasta water, then drain and set aside in a colander.

Sauté the Chicken: In a large skillet, heat the olive oil over medium-high heat. Season the chicken breasts generously with Cajun seasoning. Add the chicken, cooking for 6–7 minutes until browned and cooked through. Transfer chicken to a plate and cover with foil.

Prepare the Sauce: In the same skillet, reduce heat to medium and add the butter. Once melted, stir in minced garlic and sauté for 1 minute. Pour in the chicken broth and heavy cream, bringing to a gentle simmer. Stir well, scraping any browned bits from the skillet's bottom.

Add the Cheese: Lower heat and gradually add mozzarella, Parmesan, and cheddar cheese to the skillet, stirring constantly. Allow cheeses to melt into a smooth sauce, about 2–3 minutes. If too thick, add reserved pasta water to reach desired consistency.

Combine Ingredients: Return the chicken to the skillet, slicing if desired. Add the drained rotini and toss everything together, allowing the pasta to coat in the creamy sauce for 2–3 minutes, rewarming chicken thoroughly.

Serve and Garnish: Remove from heat and sprinkle fresh parsley over the top. Serve hot, enjoying the comforting warmth and rich flavors.