How to Make It
In a medium saucepan, combine 6 cups of the milk with the cinnamon sticks and lemon zest; bring to a boil. Add the rice and simmer over low heat, stirring often, until the rice is tender and most of the milk has been absorbed, about 1 hour. Discard the cinnamon sticks and zest. Pour the rice pudding into a serving dish.
In a small saucepan, heat the remaining 1/4 cup of milk. In a medium stainless steel bowl, whisk the egg yolks with the sugar. Stir in the hot milk. Set the bowl over a saucepan of simmering water and whisk the yolks constantly until thickened and streaks appear at the bottom of the bowl as you whisk, 6 to 7 minutes. Remove the bowl from the heat and whisk the yolk mixture to cool it slightly.
In a medium stainless steel bowl, whisk the egg whites until firm peaks form. Fold the whites into the yolk mixture and spread over the rice pudding. Dust with ground cinnamon and serve.