Place thawed chicken in the slow cooker and add cubed cream cheese, condensed cream of chicken soup, broth, and the dry Italian dressing mix. Spread around the chicken and cover.
Cook on low for about 6–8 hours, checking toward the earlier end. Remove each breast when its thickest part reaches 165°F; stir the sauce until the cream cheese is blended.
Near the end of the slow cooker stage, boil 8 ounces pasta separately according to its package until al dente, then drain.
Shred the cooked chicken and switch off the cooker. Fold chicken and cooked pasta into the warm sauce, loosening with a splash of hot water if needed; divide into six portions and serve promptly.
Notes
Refrigerate in shallow covered containers within 2 hours (1 hour above 90°F); keep at 40°F or below and use within 3–4 days.
Reheat only the portion needed to 165°F throughout.