01 - Arrange the chicken thighs in a single layer at the bottom of the slow cooker.
02 - In a medium bowl, whisk together the pesto, ranch seasoning, chicken broth, heavy cream, and Parmesan cheese until thoroughly combined.
03 - Pour the sauce mixture evenly over the chicken. Cover and cook on LOW for 4 to 6 hours, or until the chicken reaches an internal temperature of 165°F and is tender.
04 - Transfer the chicken to a serving platter, spoon the sauce over the top, and garnish with fresh basil and extra Parmesan cheese if desired.