Thoroughly mix the first 10 ingredients together in a large bowl.
Roll into balls of about 1 inch in diameter.
Heat the oil in a large frying pan over medium heat.
Add the koftas and brown all over.
Remove from the heat and drain on kitchen paper.
Heat the butter over medium heat.
Add the cumin, coriander and chillies.
Fry the spices for about a minute.
Add the stock, puree, salt, sugar and cream.
Simmer for about 5 minutes.
Add the koftas and fenugreek leaves.
Simmer for another 10 minutes, then stir in the coriander leaves.
Serve with rice and a salad.