Combine chicken pieces with tandoori masala, kasoor methi, salt, naga pickle, and 2 tbsp oil. Marinate for at least 2 hours or overnight.
Cook marinated chicken pieces in a hot pan until lightly charred and cooked through. Set aside.
Heat 3 tbsp oil in the same pan over medium heat. Add cassia bark and let it sizzle for 30 seconds.
Add garlic-ginger paste and green chili. Sauté for 1-2 minutes until fragrant.
Pour in the diluted curry gravy and bring to a simmer. Cook for 5 minutes.
Add the cooked naga chicken tikka, naga chili pickle, coconut milk, and jaggery to the pan.
Simmer for 10-15 minutes until chicken is tender and sauce has thickened to desired consistency.
Taste and adjust seasoning as needed. Serve hot with basmati rice or naan.