Preheat the oven to 150°C (300°F). Grease a large baking dish generously with butter or oil.
In a large mixing bowl, combine the chicken pieces, chopped onion, and minced garlic.
Add the canned tomatoes to the bowl and stir to combine with the chicken and aromatics.
Season the mixture with turmeric, saffron, and salt; mix thoroughly so the spices are evenly distributed.
Transfer the chicken mixture to the prepared baking dish, spreading it in an even layer.
Gently pour the chicken broth over the chicken, then dot the top with the teaspoon of butter.
Bake in the preheated oven for about 40–45 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) and is cooked through.
Remove the dish from the oven and cover loosely with aluminum foil; let the chicken rest for 10 minutes before serving.