Break egg into a bowl. Add chicken mince, garam masala powder, 1 tsp red chilli powder, 1 tbsp butter and salt and mix well.
Heat 1 tsp oil and remaining butter in a non-stick pan. Add ginger, garlic and green chillies and sauté for 1-2 minutes.
Finely slice onions, add to the pan and sauté till light brown.
Add mint leaves, coriander leaves, ¼ tsp turmeric powder and sauté for a minute. Transfer into a mixer jar, grind into a coarse mixture and transfer into a bowl.
Grind the chicken mince mixture and transfer in a bowl.
Heat the remaining oil in another non-stick pan. Add bay leaves and cashewnut paste and sauté for 6-8 minutes. Add coriander powder, remaining turmeric powder, remaining red chilli powder and sauté for 3-4 minutes. Add 2 cups water and let the mixture come to a boil.
Grease your palms with oil. Make small balls of the chicken mixture and slide them in the cashewnut gravy and cook till chicken is almost done.
Add the ground mint-coriander mixture and cook for 1-2 minutes. Add fresh cream, lemon juice and mix.
Transfer into a serving bowl, garnish with fresh red chillies and serve hot.