Pat the chicken thighs dry and lightly score them with a knife.
In a bowl, mix yogurt, Kashmiri chilli powder, garam masala, coriander powder, cumin powder, paprika, oil, lemon juice, and salt.
Coat the chicken well in the marinade and refrigerate for at least 2 hours.
Blend the boiled egg whites, cheese, garlic, milk, cream, lemon juice, salt, sugar, and oil until smooth to make the garlic sauce.
Heat oil and butter in a pan or tawa over medium heat.
Add the marinated chicken and cook for 8–10 minutes on each side until fully cooked and slightly charred.
Reduce the heat and pour over the garlic sauce. Simmer for 2–3 minutes until the sauce coats the chicken.
Garnish with lemon slices, green chillies, and coriander.
Serve hot with naan, paratha, or roti.