Soak chicken pieces in cider vinegar and water for 20 minutes.
Heat the olive oil in a large deep pot over medium-high heat. Add the onion and sauté until golden – about 10 minutes. Add chicken along with the spices: cinnamon stick, ground cinnamon, ground ginger, turmeric salt, and black pepper. Add water to cover and put on a lid. Cook until chicken is done — about 25-30 minutes. Remove chicken to a bowl and add a good pinch of sugar to sauce in pot; continue to cook until thick.
When chicken is cool enough to handle, remove skin (if using), take skin off the bones and shred.
In a food processor, grind almonds finely with 2 tablespoons sugar; transfer to a bowl. Add 1/4 cup orange flower water and stir to mix.
Preheat oven to 400°F. Coat a large baking sheet with vegetable oil. Spread out 5 sheets of brik (or warqa or phyllo) — arrange four into a cloverleaf pattern then add the fifth in the middle. Arrange shredded chicken in the center, then top with almond mixture, and finish by drizzling with the reduced pan sauce. Pull the four sides up and over the top, then cover with another sheet of brik and tuck the edges under. Gently pat down to be an even disk. Rub the top with melted butter and bake until golden — about 25 minutes.
Dust the top with confectioners sugar, lines of cinnamon in a pattern, then sprinkle on some sliced almonds, and few rose petals. Allow to cool for a few minutes to solidify before serving.