Pat the chicken breast dry and cut into bite-sized cubes, then season evenly with sea salt and black pepper.
Heat the ghee in a large skillet over medium-high heat until it begins to shimmer.
Add the chicken cubes to the skillet and sear until golden brown on all sides, approximately 5-6 minutes.
Reduce the heat to medium and stir in the minced garlic and grated ginger, sautéing for 1 minute until fragrant.
Add the garam masala, turmeric, and cumin to the pan, stirring constantly for 30 seconds to toast the spices.
Pour in the tomato puree and full-fat coconut milk, stirring to combine and scraping up any browned bits from the bottom of the skillet.
Simmer the sauce for 5-7 minutes until it thickens slightly and the chicken is cooked through.
Fold in the fresh spinach and cook for 1-2 minutes until just wilted into the sauce.
Steam the cauliflower rice in a separate pan or the microwave until tender and hot.
Serve the creamy butter chicken over the cauliflower rice and enjoy immediately.