In a mixing bowl, combine the turmeric, ground ginger, black pepper, and Ras el Hanout. Rub the spice blend thoroughly over the chicken thighs, ensuring each piece is well coated. Set aside for 15 minutes to allow the spices to infuse.

While the chicken marinates, prepare the prunes. Place the prunes in a small saucepan along with sugar, cinnamon powder, and a cinnamon stick. Add just enough water to submerge the prunes and simmer over medium heat for 5 to 7 minutes, until the prunes are soft and syrupy. Set aside once done.

In a heavy-bottomed tagine or a deep pot with a tight-fitting lid, heat the olive oil and butter over medium-high heat. Once the butter has melted and its foam subsides, add the sliced onions. Sauté them for about 4 minutes until tender and translucent. Add the minced garlic and stir to combine.

Push the onions to the sides of the pot to create space. Place the chicken thighs skin-side down in the center. Season generously with sea salt and sear the chicken for about 10 minutes, turning once, until the skin is golden and lightly caramelized.

Add the bay leaves, cinnamon sticks, chicken stock, half of the prepared prunes, and about a quarter of their syrupy liquid. Stir gently to combine, cover the pot, and let it simmer for 20 minutes until the chicken is fully cooked and tender.

Meanwhile, toast the almond slivers in a dry skillet over medium heat until golden and fragrant. Set aside for garnish.

Prepare the couscous by bringing water to a boil in a saucepan. Stir in the lemon juice, butter, raisins, and chopped prunes. Add the couscous, give it a quick stir, then turn off the heat and cover. Let it steam undisturbed for several minutes until fluffy and the liquid is absorbed.

To serve, arrange the braised chicken and onions on a large platter. Spoon over the cooking juices and top with the remaining prunes, toasted almonds, chopped cilantro, and fresh lemon zest. Serve the couscous on the side, drizzled with some of the aromatic juices from the chicken.