Chicken Biryani

This recipe is from the book CURRY, by Lizzie Collingham, published by Vintage. The book tells the history of India and its rulers through their food.
This is not necessarily how we cook biryani today, but it shows us the laborious method and number of ingredients the mughals used to cook biryani which was a ' celebratory dish' eaten at weddings.

1 whole chicken, jointed into 8-10 pieces
Marinade
2 cm pc of freshly ground ginger
6 cloves garlic crushed
2-3 ground green chillies
1/2 tsp cardamom powder
1 tsp cumin powder
1 tsp coriander powder
4 whole green chillies, slit
2 cm cinnamon stick
2 whole cloves
salt to taste
1 Tbsp lemon juice
2 tomatoes, pureed
6-8 prunes (optional)
Mix all the above ingredients and add chicken. All the pieces should be coated in the marinade. Cover and leave in fridge overnight.
350 gm red split lentils
500 ml water
4-6 Tblsp vegetable oil
2 large onions; 1/4 of one sliced, the rest chopped
400 ml yoghurt
1/4 tsp saffron, crushed and steeped in 2 tsp hot milk
500 gm basmati rice, pre soaked in water for 20 minutes
salt to taste
2 cm cinnamon stick
3 cardamom pods
3 cloves
1 1/2 litres water
6 small new potatoes, boiled until just cooked
3 hard boiled eggs, shelled and cut in half
a few sprigs of mint
100 gm blanched slivered almonds
Method
Put the lentils and water in a large pan. Bring to the boil, Turn down heat and simmer for 10 minutes. Drain and set aside.
Heat oil and fry the chopped onions until golden brown.
Take the chicken in its marinade out of the fridge, and add the onions and the cooking oil to the mixture.
Add yoghurt and mix well. Pour in the milk and saffron.
Drain the rice and put in a cooking pot with salt, cinnamon, cardamom, cloves, and 1 1/2 litres of boiling water. Simmer for 10 minutes and drain.
Fry the cooked potatoes.
Take a large casserole and put in the marinated chicken mixture at the bottom of the pot. Nestle the hard -boiled eggs in among the chicken, and sprinkle with sprigs of mint. Spread the red lentils over the meat. Then place the potatoes in a layer over the lentils. Spread the rice over the potatoes.
Fry the slices of onions and the slivered almonds in a little oil and scatter over the rice. Sprinkle a little water over the contents of the casserole. Close lid tightly and put over a high heat for 5 minutes. When the contents begin to sizzle, turn the heat to low and simmer for one hour.