First, preheat the oven to 400F.

Generously flour a clean surface, and using a rolling pin, roll out the sheet of puff pastry until it's about ¼ inch thickness.

Using a knife or pizza cutter, cut the sheet into 12 rectangles.

Line a cookie sheet with parchment, and lay 6 of the pastry pieces on it. Place a tablespoon of Nutella in the center of each piece, then moisten the edges with a little water, and top with another piece of pastry. Press down firmly with your fingertips to seal.

Lightly beat the egg in a small bowl, and brush the tops of each strudel with it. Sprinkle the sugar on top, and bake in preheated oven for 12-15 minutes, until they are puffed and golden brown.

While the strudels bake, make the frosting. In a small bowl, combine the sugar, salt, and vanilla. Add in the heavy cream a tablespoon at a time, whisking well, until it reaches a thick icing consistency. It might take more or less than indicated!

Once toaster strudels are cooked, let them cool slightly before frosting. To frost, pour the icing in a plastic zip-top baggie, and cut a corner. Drizzle the icing on top, and serve!