Heat milk in a thick-bottomed pan and bring to a boil. Reduce heat, add condensed milk and sugar and simmer for fifteen to twenty minutes till milk is thick and creamy, stirring continuously.
Take off the heat and set aside to cool. Preheat oven to 180ºC. Grease an eight-inch square baking dish with butter. Transfer the milk into a large bowl, add the whisked eggs, nutmeg powder, green cardamom powder, vanilla essence and stir gently.
Transfer this mixture into the greased baking dish and bake in the preheated oven at 180ºC for fifteen to twenty minutes or till a light golden crust is formed. Sprinkle charoli and bake the custard for a minute more.
Remove from the oven, cool and refrigerate. Serve chilled.