Here's a clue. The first time we ever saw one of these was in 1985 in Saltzburg, Austria.
Got it now?
O.K. I'll make it even easier for you.
By now, you should have guessed that this is a Salzburger Nockerl. That is, a sweet souffle Salzburg is famous for. It's a great way to use some extra egg whites you have in the fridge left over from some recipe that only used yolks.
The Nockerl is famously served with a sprinkling of powdered (confectioner's) sugar and maybe, as we had it, with a drizzle of raspberry ice cream syrup.
And by the way, I had nothing to do with the preparation of this. All credit goes to SWMBO, who remembered that we saw them coming out of kitchens in a Salzburg coffee house. They're so light that an entire one can be served to one person, as they were there. She inquired what they were and after we got home she found a recipe for them.