Combine chicken, whisked yogurt, ginger-garlic paste, and marinade spices in a bowl. Mix to coat thoroughly and marinate for 20 minutes.
Fry sliced onions in ghee over medium heat until they turn a uniform, rich golden-brown. Remove immediately and drain on paper towels.
Blend the cooled fried onions and soaked cashews with a few tablespoons of water until a smooth, velvety paste forms.
In the same pan, fry cardamom, cloves, and cinnamon on low heat for 30 seconds until fragrant.
Add marinated chicken and its juices. Sauté on medium heat for 5-7 minutes until the meat turns opaque.
Stir in the onion-cashew paste, ground coriander, cumin, and warm water. Cover and simmer on low for 15 minutes, stirring occasionally.
Stir in the garam masala. Remove from heat and let sit for 5 minutes before serving so the flavors meld.