Rinse the rice well under running cold water, then put the rice in a large bowl, cover it with lukewarm water and stir in 2 tablespoons of salt. Allow to soak for 1 to 2 hours. Drain and rinse again.
Bring medium pot of water to a boil, add 2 more tablespoons of salt, then add the rice and boil gently for 3 to 4 minutes, until almost cooked (See Note 2). Drain, rinse and set aside to drain completely.
In the same pan, melt 6 tablespoons of the butter and sauté the almonds until slightly golden, about 4 minutes (2 minutes if using Marcona almonds). Add the chopped dried apricots, cook for a 3 more minutes, then stir in the advieh spice blend, half a teaspoon of white pepper, half teaspoon salt and half of the rice.
Gently flatten down the rice, tapping to flatten using your fingers or spatula, then spoon the remaining rice on top.
In a small bowl crush saffron threads and stir in 2 tablespoons of hot water. Allow saffron to bloom, set aside.
Melt remaining 2 tablespoons of butter and pour over the top, along with 3 tablespoons of water. Cover the pan with a tight lid and cook on the lowest possible heat for 35 minutes (I use a heat diffuser on top of burner like when using a tagine). Turn off the heat, drizzle the saffron and its water over, cover with a tea towel, put the lid back on and set aside for 10 minutes.
Serve hot, using a large spoon, scooping the two layers of rice together, or toss to mix.