In a large pot, bring salted water to a boil. Add the rigatoni and cook according to package instructions until al dente. Drain and set aside.
In a skillet, heat olive oil over medium-high heat. Add the chicken pieces, season with salt and pepper, and sauté until the chicken is cooked through and browned, about 6-8 minutes. Remove the chicken from the skillet and set aside.
In the same skillet, add the butter and minced garlic. Sauté for 1-2 minutes until fragrant but not browned. Slowly whisk in the heavy cream, stirring continuously.
Once the cream is heated through, reduce the heat to low and add the grated Parmesan cheese. Stir until the cheese melts and the sauce becomes creamy. Season with salt and pepper to taste.
Return the cooked chicken to the skillet, add the rigatoni, and toss everything together until well coated with the sauce. Cook for another 2-3 minutes to heat through.
Divide among plates, garnish with chopped fresh parsley, if desired, and serve immediately.