Place the rice in a large bowl and wash in 5 changes of cool water, agitating with your hands with each washing. The last change of water should run off mostly clear. Drain in a colander and set aside.

Preheat the oven to 350 degrees F.

Stuff the cavity of the chicken with the whole onion and garlic cloves and season well both inside and out with salt. Using a pastry brush, brush the chicken all over the outside with 1 tablespoon of the saffron water. Place the chicken in the oven and bake until golden brown and cooked through, about 1 1/2 hours. Remove from the oven and let rest briefly before carving into serving pieces and serving with the rice.

While the chicken is roasting, prepare the rice. Place the orange peel in a medium saucepan and cover with water. Bring to a boil then drain. Combine the drained peel, carrot strips, sugar, and 1 cup of water in the same (rinsed) saucepan and bring to a boil. Boil for 10 minutes; strain and set aside.

Rinse the raisins and currants under cool running water and set aside.

In a medium skillet cook the sliced onions in 2 tablespoons of the butter until soft and lightly caramelized, about 10 minutes. Add the raisins and stir to combine. Cook for 2 to 3 minutes, then remove from the heat and set aside to cool.

Combine the rose petals, cinnamon, allspice, and cumin in a small bowl and stir to blend.

In a large, nonstick saucepan, bring 8 cups of water to a boil. Add 2 tablespoons of salt and add the washed and drained rice. Bring to a boil and cook until tender, about 8 minutes, stirring occasionally to keep rice from sticking to the bottom. Drain rice in a large, fine-meshed sieve and rinse briefly under warm water. Set aside.

In the same pot heat 4 tablespoons of the remaining butter. Mix 2 cups of the rice, the yogurt, and 2 teaspoons of the saffron water in a small bowl and then spread over the bottom of the pot using the back of a spoon. Add 2 cups more rice, smooth the top with the back of a spoon, then sprinkle 1/4 of the orange peel-carrot mixture over the rice. Sprinkle half of the spice mixture and then continue adding layers of rice and orange peel-carrot mixture until you have used all of the rice. Cover and cook for 15 minutes over medium heat. In a small bowl combine the remaining 2 tablespoons of butter, saffron water, and 3 tablespoons of water and pour this mixture over the rice.

Cover with a clean dish towel and then cover pot with the lid so that you now have a very tight seal on the pot; reduce the temperature to low and continue to cook for 50 minutes longer, undisturbed. Remove the pot from the heat and transfer to a cool surface, such as a wet kitchen towel, and allow to cool for 5 minutes, undisturbed (this will help to release the crusty rice layer on the bottom of the pot.) Remove the lid and remove a small ladleful of the saffron rice and set aside; this will be used as a garnish. Using a spatula or large spoon, transfer the rice to a serving platter, alternating layers of raisin-onion mixture and cooked rice, mound the rice in the shape of an inverted cone. Arrange the chicken around the edges of the platter, then sprinkle the top of the rice mound with some of the reserved saffron rice. Using a wooden spatula, carefully release the rice "crust" from the bottom of the pot and unmold onto a separate small platter. Serve this "crust" on the side; this is considered a treat! Garnish the platter of rice with the almonds and pistachios and serve immediately.