Heat the ghee in a large skillet over medium-high heat.
Season the cubed chicken breast with sea salt and black pepper, then sear in the skillet until golden brown on all sides.
Remove the chicken from the pan and set it aside on a plate.
In the same skillet, add the diced yellow onion and sauté until translucent and soft, about 3-4 minutes.
Stir in the minced garlic and grated fresh ginger, cooking for 1 minute until fragrant.
Add the garam masala, turmeric powder, and ground cumin, stirring constantly to toast the spices for 30 seconds.
Pour in the tomato puree and coconut milk, stirring to combine and scraping up any browned bits from the bottom of the pan.
Return the chicken to the skillet and simmer for 5-7 minutes until the sauce thickens and the chicken is cooked through.
Fold in the fresh baby spinach and stir until just wilted before serving warm.