Preheat oven to 375° Fahrenheit. Place chicken thighs on cutting board. Season generously with salt and black pepper to taste, then flip chicken thighs over and season other side.
Heat large, oven-safe skillet over medium-high heat. When pan is hot, add ghee. Continue warming pan until ghee is melted, swirling pan occasionally to move ghee around to coat.
When ghee is melted, place seasoned chicken thighs in skillet, skin-side down. Place thighs so they can cook evenly without needing to be moved.
Cook chicken thighs skin-side down, undisturbed, 7 minutes, or until skin-side is evenly browned and releases easily from pan. If skin sticks, continue cooking until skin releases easily.
Once chicken thighs are ready, place skillet in preheated oven. Cook 13 minutes, or until internal temperature of chicken thighs reaches 160° Fahrenheit.
When chicken thighs are ready, carefully remove skillet from oven and transfer chicken thighs to plate. Set plate aside to rest and return skillet to stovetop over medium-high heat. Note: use potholder from this point forward. Skillet will stay very hot.
Place apple slices and Craisins in skillet. Cook 2 to 3 minutes or until apples are lightly golden-brown and just softened.
Add garlic to skillet. Sauté garlic, stirring constantly, 30 to 60 seconds or until garlic is just fragrant.
Add cranberry apple juice, chicken stock, and rosemary to skillet. Stir to incorporate, then increase heat to high and bring mixture to boil. Once mixture begins to boil gently, immediately reduce heat to low. Simmer 2 to 4 minutes, stirring occasionally, until sauce has reduced slightly.
After simmering, taste sauce and add more salt and/or pepper if desired. Return chicken thighs to skillet and cover with spoonfuls of sauce. If needed, return skillet to low heat just until chicken is warmed-through, then serve chicken with desired sides and plenty of sauce.