Bring milk to a simmer in a saucepan; add vanilla bean and stir. Mix rice and white sugar into simmering milk; add lemon peel. Bring liquid to a boil, reduce heat to low, and simmer, stirring constantly, until rice is tender, 20 to 25 minutes. Transfer saucepan to the refrigerator and chill, at least 30 minutes.
Whisk egg yolks and orange liqueur together in a bowl. Beat egg whites in a separate bowl until foamy. Continue to beat egg whites until stiff peaks form. Lift your beater or whisk straight up: the egg whites will form sharp peaks.
Preheat oven to 350 degrees F (175 degrees C). Grease or line a 9-inch cake pan with parchment paper.
Remove vanilla bean and lemon peel from rice. Stir raisins and orange zest into rice; add egg yolk mixture and stir. Softly fold egg whites into rice mixture. Slowly pour rice mixture into the prepared cake pan.
Bake in the preheated oven until set, about 1 hour. Sprinkle confectioners' sugar over rice cake.