Season chicken with basil, oregano, rosemary, salt and pepper, to taste.
Melt butter in a large skillet over medium high heat. Add chicken, skin-side down, and sear both sides until golden brown, about 2-3 minutes per side; drain excess fat and set chicken aside.
Place potatoes into a 6-qt slow cooker. Stir in olive oil, garlic and thyme; season with salt and pepper, to taste. Add chicken to the slow cooker in an even layer.
Cover and cook on low heat for 7-8 hours or high for 3-4 hours, or until the chicken is completely cooked through, reaching an internal temperature of 165 degrees F.
Serve immediately, sprinkled with Parmesan and garnished with parsley, if desired.