Please note: you will also need 4 bbq skewers to cook the chicken
First of all, you need to marinade the chicken for at least 20 minutes, but ideally either overnight or for a few hours.
Chop the chicken into chunks, add in the marinade ingredients (ginger, garlic, lemon juice, garam masala, salt, cinnamon, coconut yoghurt), cover with cling-film and pop in the fridge to marinade.
As explained above, I cooked the chicken on the barbecue (long enough to blacken the outside, but not worrying about cooking all the way through as I was going to add it straight into the sauce to cook through). Just grill the chicken if you can't barbecue it.
To get the sauce ready, melt the teaspoon of butter in a deep frying pan, then add the garlic and chilli and cook gently for a couple of minutes.
Stir through the cumin, paprika, coriander, cayenne pepper and cinnamon and then add in the passata.
Add in about 250 ml water and bring to a gentle simmer
Add in your barbequed (or grilled) chicken, stir to coat, pop a lid on and simmer gently for about 20 minutes to give the chicken a chance to cook through. If the sauce dried out too much add a little extra water.
In a small saucepan, gently warm through the coconut yoghurt (if it's warm it won't curdle when you add it to the sauce). Once warm, add into the sauce and stir through. If the sauce is still watery then turn up the heat and bubble away excess moisture so that you have a nice thick sauce. Season with salt.