Murgh makhani (Butter chicken)

Chicken

• 800 g chicken thigh fillets, each thigh cut into 8 pieces
• 30 g lemon juice
• ¼ tsp salt
• 150 g natural yoghurt
• 120 g tandoori paste (see Tips)
• oil, for greasing

Butter sauce

• 2 tsp cumin seeds
• 2 tsp coriander seeds
• 2 cm cinnamon quill
• 1 black cardamom pod
• 1 tsp fenugreek seeds
• 45 g ghee (see Tips)
• 1 - 2 brown onions (approx. 180 g), cut into halves
• 20 g ginger paste (see Tips)
• 10 g garlic paste (see Tips)
• 1 tsp salt
• 2 fresh long green chillies, trimmed and cut into halves (optional)
• 20 sprigs fresh coriander, leaves, stalks and roots, cut into thirds, plus extra leaves for garnishing (see Tips)
• 400 g canned whole tomatoes
• 70 g water
• 70 g cashews, plus extra for garnishing
• 40 g unsalted butter
• 1 tsp garam masala (see Tips)
• 100 g pouring (whipping) cream