In a blender, combine garlic, ginger, green chilies, and onion. Add a little water and blend into a thick, smooth paste.
Heat 1 tablespoon of oil or ghee in a pan or karahi. Add whole garam masala (cardamom, cloves, cinnamon, black pepper) and sauté for a few seconds until fragrant.
Add the blended ginger-garlic-onion paste and cook on high heat until oil starts to separate from the masala.
Add the chicken pieces and stir on high heat until they change color. Keep stirring for even cooking.
Mix in yogurt, salt, and white pepper, then add 1 cup of water. Stir well to combine.
Cover the pan and cook on medium-low heat for 25 minutes until the chicken is tender and cooked through.
Turn the heat to low and add fresh cream and a cube of butter. Mix gently, then increase to medium heat and cook until oil starts to separate around the edges of the karahi.
Cover the pan again and cook on low heat for 5 more minutes to let the flavors meld.
Sprinkle white pepper and garnish with julienned ginger. Serve hot with naan, roti, or kulcha for an authentic Pakistani dining experience.