For the rhubarb groats, peel off the rhubarb and cut into small pieces. Mix with the spices and cook very soft. Whisk the semolina with a little water, add to the boiling puree and let it soak for 20 minutes. If the groats become too firm, stir gradually with the rest of the water. Finally fold in the stiffly beaten egg whites and let cool.
For the vanilla sauce, cook a sauce from the sauce powder, milk and sugar and stir in the egg yolks.