Boil the heavy cream with sugar, salt, and vanilla sugar and stir in the chopped up chocolate.

Remove from heat and let cool.

Cream the butter and slowly stir into the chocolate.

Line a baking sheet with parchment paper.

Using a piping bag fitted with a round nozzle, make balls on the paper.

Chill and let harden.

Before glazing, let them sit at room temperature for a short time.

Melt the dark chocolate, let cool, dip the truffles using a fork, and let excess drip off.

Roll in cocoa powder and shake off excess.