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 until melted and shimmering.
Add the chicken to the skillet and sear for 3-4 minutes until golden brown on all sides, then remove and set aside.
In the same skillet, add the diced yellow onion, minced ginger, and minced garlic, sautéing for 3 minutes until softened and fragrant.
Stir in the garam masala, turmeric, and cumin, toasting the spices for 30 seconds to release their oils.
Pour in the tomato puree and full-fat coconut milk, stirring well to combine and scraping any browned bits from the bottom of the pan.
Return the chicken to the skillet and simmer the sauce for 5-7 minutes until it thickens and the chicken is fully cooked.
Fold in the fresh baby spinach and stir until just wilted into the sauce.
Garnish with chopped fresh cilantro and serve immediately.