Cut the chicken breast into bite-sized 1-inch cubes and season lightly with a pinch of the sea salt and black pepper.
Heat the ghee in a large non-stick skillet over medium heat until melted and shimmering.
Add the finely diced yellow onion to the skillet and sauté for 3-4 minutes until soft and translucent.
Stir in the minced garlic, grated fresh ginger, garam masala, turmeric, and cumin, cooking for 60 seconds until the spices are toasted and fragrant.
Add the chicken cubes to the pan and cook for 3-5 minutes, turning occasionally until the edges are golden brown.
Pour in the tomato puree and the remaining sea salt and black pepper, then reduce the heat to low and simmer for 10 minutes.
While the chicken simmers, steam the cauliflower rice in a separate covered pan with a splash of water for 5 minutes until tender.
Stir the full-fat coconut milk into the chicken mixture, folding it in until the sauce is creamy and uniform in color.
Plate the steamed cauliflower rice and top with the butter chicken, garnishing with freshly chopped cilantro before serving.