Pat the chicken dry. Thaw frozen shatkora, rinse it, remove any seeds and cut the wedges into 2 to 3cm pieces. Prepare the potatoes in even 4cm chunks.
Heat the oil in a wide, heavy based pan over a medium heat. Fry the bay leaves, cassia, black and green cardamom, cloves and dried red chillies for about 45 seconds, until aromatic.
Add the onions and cook for 10 to 12 minutes, stirring regularly, until evenly golden. Add the green chillies and Garlic and Ginger Paste, then cook for 1 minute.
Reduce the heat to medium low. Add the coriander, cumin, turmeric, Kashmiri chilli powder and optional hot chilli powder. Pour in the measured 50ml hot water and stir for 2 minutes, until it has mostly evaporated and oil appears around the masala.
Add the chicken and salt. Cook over medium high heat for 8 minutes, turning the pieces until opaque and thoroughly coated with the masala.
Add the tomatoes and cook for 5 minutes, pressing them until soft. Stir in the prepared shatkora and potatoes and coat them carefully in the masala.
Pour in the measured 400ml hot water and bring to a gentle simmer. Cover and cook over a low heat for 30 minutes, stirring carefully once or twice, until the potatoes are tender and the chicken is thoroughly cooked to at least 75°C in the thickest part away from the bone.
Uncover and simmer for 5 to 8 minutes, until the gravy reaches your preferred consistency. Stir in the garam masala and coriander, cover and rest off the heat for 10 minutes before serving.