To your slow cooker add the chicken breasts, heavy cream, chicken broth, butter, cream cheese, salt, Italian seasoning, pepper, and garlic powder.
Cover and cook for 2 hours on HIGH or 3 to 4 hours on LOW.
Remove chicken and shred it. Return chicken to slow cooker and add pasta & parmesan. Mix to combine. Recover and cook for 30 minutes on HIGH or until pasta is tender.
Remove lid and stir on more time. Top with parsley and extra parmesan cheese if desired.
I have had reader feedback that the pasta needs to be cooked before adding into the crock pot. I haven't run into this issue with my crock pot, but every slow cooker is different and cooking times may vary. Option A) Add the uncooked pasta and cook in the crock pot with the sauce, chicken, and cheese until the pasta is al dente. Option B) Cook the pasta (according to package directions) in boiling water until al dente, and then add to the crock pot as directed.
I used frozen chicken breasts for this recipe, and they needed just under 3 hours on HIGH to reach 165 degrees F internal temperature. If you're using raw chicken (not frozen) start checking your chicken around 2 hours.
If you want to cook this recipe on LOW temp, it takes about 5 to 6 hours with frozen chicken or 3 to 4 hours on HIGH. This important thing is to make sure the chicken is cooked through before moving onto to finish the recipe.