Peel the rhubarb and cut into pieces, sugar-coat with 150 g sugar and let stand until it pulls in juice.
In the meantime, make a shortcrust pastry from flour, 65 g sugar, 1 egg, butter, baking powder and vanilla sugar. Press the shortcrust pastry into a springform pan and pull up one edge.
Bring 1/2 liter of rhubarb juice (if the juice is not enough, fill up with water) with vanilla pudding powder, mix with the rhubarb and pour everything onto the shortcrust pastry. Bake at 200 ° C for 45 minutes.
Beat 3 egg whites and icing sugar until stiff and bake for the last 10 minutes.