Rinse the basmati rice under cold water until clear, then combine with 0.5 cup water in a small pot, bring to a boil, cover, and simmer for 15 minutes.
While rice cooks, dice the chicken breast into bite-sized pieces and season with sea salt and black pepper.
Heat the ghee in a large skillet over medium-high heat and sauté the diced yellow onion until translucent and soft.
Stir in the minced garlic and grated ginger, cooking for one minute until the mixture becomes highly fragrant.
Add the chicken to the skillet and brown on all sides for about 5 minutes.
Sprinkle in the garam masala, turmeric, and ground cumin, stirring well to coat the chicken and toast the spices.
Pour in the tomato puree, reduce heat to low, and simmer for 10 minutes until the chicken is cooked through and the sauce thickens.
Stir in the full-fat coconut milk to create a rich, velvety texture and heat through for another 2 minutes.
Fluff the rice with a fork and serve the butter chicken on top, garnished with freshly chopped cilantro.