Preheat your oven to 375°F (190°C).
In a large skillet, heat the olive oil over medium heat. Add the chopped onion and garlic, sautéing until translucent.
Season the chicken thighs with salt and pepper, and add them to the skillet. Cook until the chicken is browned on all sides.
Stir in the ground cinnamon, ginger, turmeric, and nutmeg, coating the chicken evenly with the spices.
Pour in the chicken broth, reduce the heat to low, cover, and simmer for 20 minutes, or until the chicken is cooked through.
Remove the chicken from the skillet, shred it using two forks, and set aside.
In the same skillet, add the beaten eggs to the remaining liquid and cook, stirring constantly, until the eggs are scrambled and cooked through.
Combine the shredded chicken, scrambled eggs, parsley, and cilantro, mixing well to create the filling.
Brush a round baking dish with some of the melted butter. Lay down a sheet of phyllo dough, brushing it with butter before adding the next layer. Repeat this process until you have 4 layers.
Spread the chicken mixture over the phyllo base, then cover with the remaining 4 sheets of phyllo, brushing each with butter as before.
Tuck the edges of the phyllo sheets into the sides of the dish to seal the pie.
Bake in the preheated oven for about 40 minutes, or until the pastry is golden brown and crisp.
Allow the bastilla to cool slightly, then dust with powdered (icing) sugar and ground cinnamon before serving.