In a large bowl, whisk together the yogurt, lemon juice, ghee or oil, garam masala, cumin, coriander, cayenne pepper (if using), salt, and pepper.
Add the chicken to the marinade and mix well to coat. Cover and refrigerate for at least 2 hours or overnight.
Preheat the grill or oven to medium-high heat. Remove the chicken from the marinade, letting any excess liquid drip off.
Grill the chicken for 5-7 minutes per side, or until it's cooked through and slightly charred. Alternatively, bake in the oven for 15-20 minutes, or until cooked through.
Garnish with cilantro and serve with basmati rice, naan bread, or your favorite sides.