In a small bowl, combine the chicken, Greek yogurt, half of the garam masala, turmeric, sea salt, and black pepper; marinate for at least 15 minutes.
Heat the ghee in a large skillet over medium heat and sauté the diced yellow onion until it becomes translucent and fragrant.
Stir in the minced garlic and grated ginger, cooking for 1 minute until their aromas are released.
Add the marinated chicken to the skillet and cook until browned on all sides, approximately 5 minutes.
Pour in the tomato puree and the remaining garam masala, then reduce the heat to low and simmer for 10 minutes until the chicken is cooked through.
Stir in the full-fat coconut milk to create a velvety, rich sauce and remove the skillet from the heat.
Serve the chicken and sauce over a bed of warm, cooked basmati rice and garnish with freshly chopped cilantro.