Spicy stuffed chicken

Ingredients

• 1 chicken, about 1.8kg, boned
• 1 tsp cumin seeds
• 1 tsp coriander seeds
• 8 green cardamom pods
• 1 tbsp groundnut oil
• 30g butter
• 2 onions, peeled and finely diced
• 6 garlic cloves, peeled and finely chopped
• 3cm piece of ginger, peeled and grated
• 2 red chillies, deseeded and finely diced
• 2 tsp ground turmeric
• 1 tsp garam masala
• A handful of coriander leaves, finely chopped
• About 80g plain full-fat yoghurt
• About 2 tbsp olive oil
• Sea salt
• freshly ground black pepper