Heat half the oil in a large lidded saucepan. Add the chicken and cook until starting to turn golden brown. Remove and set aside.
Heat the remaining oil in the pan, add the onion, pinch of salt, fenugreek, cardamom pods, garam masala, turmeric and chilli powder and fry for about 5mins until the onions become transparent.
Add the ginger, garlic and chillies and cook for a further 5mins.
Add the tomatoes and fill the can with water, add and bring to a boil. Add the cashew nuts and cook for 5mins.
Pour the sauce into a blender and blitz until smooth. Return to the pan, add the cream and chicken, stir together and simmer for about 20mins until the chicken is cooked and the sauce has thickened. Top tip: If the sauce becomes too thick, add a little hot water.
Season and serve with boiled rice and naan.