Prep the slow cooker. Lightly grease the crockpot insert or use a liner to reduce sticking and make cleanup easy.
Season the chicken. Pat the thighs dry and sprinkle both sides with pepper, onion powder, and a small pinch of salt. If your ranch mix is very salty, go easy on added salt.
Layer ingredients. Place the chicken thighs in the slow cooker in an even layer. Scatter the cream cheese chunks on top.
Sprinkle the ranch seasoning and dried dill over everything. Add the minced garlic.
Add liquids and butter. Pour the chicken broth and heavy cream around the chicken, then dot the top with butter.
Cook low and slow. Cover and cook on Low for 4–6 hours (boneless usually 4–5; bone-in 5–6). Alternatively, cook on High for 2.5–3.5 hours.
The chicken should be tender and at 165°F internal temperature.
Shred or leave whole. When done, you can serve the thighs whole or shred the meat right in the crockpot for a pulled-chicken style. Stir to mix the creamy sauce.
Thicken if needed. If you want a thicker sauce, sprinkle in xanthan gum while whisking vigorously. Let it sit for 3–5 minutes to thicken.
Start with 1/4 teaspoon; add a little more only if needed.
Finish and serve. Taste and adjust salt. Garnish with chopped parsley or chives. Serve over cauliflower rice, sautéed spinach, zoodles, or with roasted broccoli.