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