Sieve the cornstarch and flour into a bowl, add salt, sugar, vanilla sugar, eggs and milk. Mix with a hand mixer to form a smooth dough. Let it soak for about 20 minutes.
First, hold the wafer wheels in hot fat to heat it up. Then dip into the dough twice so that the top edge is not covered by the dough mixture. Then hold in hot fat (approx. 0.5 minutes) until the waffle is lightly browned. Make the remaining roses in the same way.
Drain the roses on kitchen paper and dust with powdered sugar.