In a bowl, combine the cubed chicken breast with Greek yogurt, garam masala, and turmeric powder. Let marinate for at least 15 minutes.
Rinse the basmati rice under cold water until clear. Place in a small pot with 0.5 cup of water and the saffron threads. Bring to a boil, then reduce to a simmer, cover, and cook for 15 minutes.
While the rice cooks, heat the ghee in a large skillet over medium heat. Add the diced yellow onion and sauté until translucent.
Stir in the minced ginger and garlic, cooking for 1 minute until fragrant.
Add the marinated chicken to the skillet and cook until browned on all sides.
Pour in the tomato puree, sea salt, and black pepper. Stir well and simmer for 10 minutes until the chicken is cooked through.
Stir in the full-fat coconut milk to create a creamy sauce and simmer for an additional 2 minutes.
Fluff the saffron rice with a fork and serve the butter chicken over the top.