1. Make turkey: Preheat oven to 375ºF. In a bowl, mix 3 Tbsp. chopped thyme with 6 Tbsp. butter, 1 tsp. salt and 1/2 tsp. pepper. Set aside.
2. Starting at neck end of turkey, gently slide your fingers between skin and breast to loosen skin. Smear seasoned butter under skin, all over breast meat. Season cavity with salt and pepper, then stuff in onion, apple, lemon and thyme sprigs. Tie legs loosely together with kitchen twine and tuck wings under.
3. Using your fingers, smear remaining 2 Tbsp. butter over skin. Season with salt and pepper. Place turkey on rack in large roasting pan. Pour 1 cup chicken broth into pan. Roast turkey 30 minutes. Reduce oven temperature to 350ºF. Rotate pan and roast another 30 minutes. Pour 1 cup broth over turkey, rotate again and roast another 30 minutes. Repeat 2 more times, covering breast loosely with foil if it browns too quickly. Roast turkey until a meat thermometer stuck into thickest part of thigh reads 175ºF, 3 to 3 1/2 hours total. Remove turkey to a platter, tent loosely with foil and let rest for 30 minutes. Strain pan juices through a sieve, skimming off and reserving 4 Tbsp. fat. Set aside rest of pan juices and discard remaining fat.
4. Make gravy: In a large saucepan over medium-high heat, warm oil. Add neck bone, giblets, onion, celery, carrot, thyme sprig, bay leaves, cinnamon stick and apple and cook, stirring, for about 10 minutes, until neck bone is lightly browned and vegetables are softened. Add apple cider and chicken broth, stir to release any browned bits on bottom of pan, bring to a boil, reduce heat to low and simmer for 45 minutes. Strain liquid through a sieve, discarding solids.
5. Place roasting pan on stove over 2 burners on medium heat and return reserved 4 Tbsp. fat to pan. Add flour and whisk together until well blended. Cook 2 minutes, whisking constantly. Add cider mixture and pan juices and whisk until mixture comes to a boil, then reduce heat and simmer until thickened, stirring often, about 15 minutes. Serve with turkey.