Heat the butter in a saucepan, add the chicken and fry for 3 minutes. Finely chop the onion, ginger, garlic and chilli in a food processor or with a knife. Add to the chicken and fry for 5 minutes, stirring until lightly browned.
Mix in the spices and cook for 3–4 minutes until well coloured. Stir in the stock and cream, then simmer for 10 minutes, stirring occasionally until the chicken is tender.
Stir in the chopped coriander and lemon juice to taste. Cook for 1 minute, then garnish with extra coriander. Serve with rice and naan bread.