Cook rigatoni according to package instructions for al dente and set aside.

To a large slow cooker, add the heavy cream, chicken broth, butter, salt, pepper, garlic, and chicken. Stir to combine. Cover and cook until the internal temperature of the chicken is 165°F, 3 to 5 hours on low heat.

Remove the chicken to a cutting board. When it is cool enough to handle, slice crosswise into bite-size pieces.

Add cooked chicken, cooked pasta, and parmesan cheese to slow cooker. Stir gently to combine. Increase heat to high to reheat pasta and chicken.

Serve topped with additional parmesan cheese.