For the chocolate rice casserole, pre-cook the rice in water for 4 minutes. Strain rice and rinse. Bring milk to a boil in a saucepan, add salt, cinnamon bark and lemon zest, and steam rice.
Separate eggs and beat egg whites until stiff. Beat yolks, butter, sugar and vanilla sugar until fluffy. Then add the rice and fold in the beaten egg whites, sprinkle the grated chocolate on top and spread the remaining rice mixture on top.
Bake the chocolate ice cream casserole at 180 °C for approx. 45 minutes.