Cut chicken breast into 1-2″ chunks, and season with salt and pepper. Set aside.
In a large heavy pan, saute onions in coconut oil for 15 minutes over medium-low heat until softened and starting to brown. Add cumin seeds, ginger, and garlic and saute another 15 minutes or until onions are caramelized, they will be golden brown and melty. Let cool for a few minutes.
Put onion mixture in a blender or food processor with yogurt, tomato paste, cashews (or almonds), broth, and salt. Blend until mostly smooth or leave some texture if you prefer that. The consistency will be thick. Set aside the korma sauce.
In a small bowl mix together Kashmiri chili powder, garam masala, coriander, cumin, turmeric, black pepper, cardamom and cinnamon. Add ghee and the spices to a pot or large pan. Stir over low heat for about a minute.
Turn up to medium heat and add the chicken stirring a minute to coat all the pieces with the spices, add the serrano chilies and the korma sauce. Bring to a simmer for about 8- 10 minutes stirring frequently to keep the sauce from sticking to the pan. If you prefer a thinner sauce add more broth or water (adjust the spices accordingly, adding more salt or garam masala if needed). Once the chicken is cooked through remove from heat.
