Skin the chicken and cut each chicken joint into two (ie separate leg from thigh). Cut large thighs into two. Grind the next 8 ingredients (starting with poppy seeds and finishing with cloves) in a coffee grinder until fine.

In a heavy saucepan, melt the butter over a medium heat and fry the onions, ginger and garlic until the onions are soft and translucent, but not brown. Add the ground ingredients and continue to cook for 2 minutes.

Add the chicken and salt. Stir and cook for 2 minutes. Switch off the stove and keep the chicken covered. Soak the saffron strands in the hot milk and set aside. Preheat the oven to 180C/350F/gas 4. Bring a large pan of water to boiling point and add the rice and the remaining ingredients. Bring back to the boil and let it boil steadily for 2 minutes. Drain the rice without discarding the whole spices, then pile it on top of the chicken. Dot the surface of the rice with the saffron and milk.

Make a sticky dough with plain flour and water to seal the pan. Seal the entire edge of the saucepan lid with the dough and place it on the saucepan, pressing it down firmly. Alternatively, soak a piece of greaseproof paper and squeeze out the water. Place it on top of the rice and cover the saucepan with a piece of foil. Place the lid (without the dough) on top and cook in the centre of the oven for 1 hour.

Transfer the biryani to a serving dish and serve garnished with fried onions.