Heat 1 tablespoon oil in a heavy bottomed pan over high heat. Add chicken. Cook until all the sides of the chicken pieces are well browned. Remove chicken from pan. Set aside.
Heat 1 tablespoon oil and butter in the same pan over medium- high heat. Add cinnamon stick and sauté for a few seconds. Add onions. Sauté, stirring occasionally, for 3-4 minutes or until the onions are browned. Add ginger and garlic. Sauté, stirring occasionally occasionally, for 1 minute or until aromatic.
Add cumin powder, garam masala and red chili powder. Sauté, stirring constantly, for 1 minute. Add tomato purée. Stir and fry for a minute. Add cream, yogurt and milk. Season with salt. Bring the mixture to a boil. Reduce heat and simmer for 3-4 minutes.
Add chicken and kasuri methi. Add cashewnut paste if you are using. Stir. Cover and cook for 5-6 minutes or until chicken pieces are cooked through. Remove from heat.