Make the brine: In a medium pot, bring 2 cups water to a boil and add salt, honey, bay leaves, and garlic cloves. Reduce to a simmer, stirring occasionally, and cook for 5 minutes. Remove from heat, add saffron powder, stir to combine.
In a large bowl, combine brine mixture and remaining 6 cups water. Add chicken legs, cover with plastic wrap, transfer to refrigerator, and let sit 8–12 hours.
Braise the chicken: Preheat the oven to 400°F. Cut the leeks into thin circles and wash in water to remove grit. Place leeks in a large roasting pan. Remove the chicken legs from the brine and place them, skin side down, over the leeks.
Bring 1⁄2 cup water to a boil. Add the saffron powder and stir to combine. Pour the mixture into the roasting pan. Add bay leaves and cover with foil. Roast for 45 minutes.
Remove the foil, turn the chicken legs skin side up, and roast until the chicken skin is golden and crispy, about 15 minutes more. Serve with the leeks and the juices.