Heat the milk. When it starts boiling add butter to it & let it melt completely. Separate the yolk & white of the eggs. Beat egg white with powdered sugar until it forms a soft peak. Add egg yolks & beat well. Mix the flour & baking powder & add this to the egg mixture. Beat well. Add milk & butter mixture & vanila essence to the cake mix & Mix well.Pour the batter into a buttered baking dish. Bake at 180 degree for 20 - 30 minutes.