Butter chicken

Name: Butter chicken
Cuisine: Indian
Ingredients: 750g (1 lb 10 oz) skinless, boneless chicken (thighs and breast), cut into bite-size pieces; 10g (½ oz) ginger root, peeled and grated (shredded); 3 large garlic cloves, peeled and grated (shredded); 2 tsp tandoori masala; 1 tsp ground cumin; 1 tsp ground coriander; 1 tsp ground black pepper; 1 tsp salt; 2 tbsp yoghurt; juice of ½ lemon; 30ml (1 fl oz/2 tbsp) sunflower oil; 500g (1 lb 2 oz) tomatoes; 50g (2 oz) butter; 20g (3/4 oz) ginger root, peeled and grated (shredded); 6 large garlic cloves, peeled and grated (shredded); 1 tsp tomato purée (paste); 1 tsp tandoori masala; 1 tsp chilli powder; 1 tsp sugar; 30g (1½ oz) ground cashew nuts; 30ml (1 fl oz/2 tbsp) double (heavy) cream; 6–8 green cardamom seeds, crushed; 2 tsp dried fenugreek leaves (kasoori methi); TO SERVE; your choice of Indian flatbreads or rice