Cook the rigatoni according to package instructions in a large pot of salted boiling water until al dente. Drain and set aside.
In a skillet over medium heat, melt 2 tablespoons of butter. Add the diced chicken and season with salt and black pepper. Cook for about 5-7 minutes until golden brown and cooked through. Remove the chicken from the skillet and set aside.
In the same skillet, add the remaining butter and minced garlic. Sauté for about 1-2 minutes until fragrant.
Pour in the chicken broth and bring to a simmer. Let it cook for about 3-5 minutes.
Reduce the heat to low, then whisk in the heavy cream and Italian seasoning. Let it simmer gently for another 2-3 minutes.
Gradually stir in the grated Parmesan cheese until melted and the sauce is smooth. Add salt and pepper to taste.
Return the cooked chicken to the skillet and mix well to combine everything.
Add the cooked rigatoni to the skillet, tossing to coat the pasta evenly in the creamy sauce.
Garnish with chopped fresh parsley before serving.