Grind together the ginger, garlic, almond and cayenne pepper in an electric blender.
Heat 3 tablespoons of the butter and brown the onions.
Remove onions and set aside.
Heat remaining 3 tablespoons of butter and fry the ground ginger-nut paste for 2 or 3 minutes.
Add the lamb, sprinkle with 1-teaspoon salt, and fry until brown.
Put in water, cover and simmer about 1 hour.
In a bowl, combine the bay leaf, cardamom, cloves, cinnamon, turmeric, remaining teaspoon salt, mint leaves, green chili, coriander leaves, limejuice and yogurt. Mix well.
When lamb cubes are tender and very little gravy remains, add spiced yogurt. Stir well.
Butter a heavy casserole. Put in layers of lamb, browned onion, and rice. Repeat until all ingredients are used.
Dissolve the saffron in 1 tablespoon of milk.
Pour the remaining 3-tablespoons milk over the top of the casserole. Then sprinkle on the saffron milk. Cover tightly. Seal edges of the casserole with aluminum foil.
Put in a 300 degree oven for 40 minutes.
Sprinkle with rose water before serving.