Finely chop the dark chocolate and place it in a medium bowl.

In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Remove from heat.

Pour the simmering cream over the chopped chocolate. Let it sit for about 2 minutes, then stir until smooth and completely melted.

Stir in the finely chopped hazelnuts and vanilla extract until well combined.

Cover the bowl with plastic wrap and refrigerate for about 2 hours or until the mixture is firm enough to handle.

Once chilled, use a small spoon or a melon baller to scoop out the mixture and roll it into small balls.

Roll the formed truffles in cocoa powder or finely chopped hazelnuts to coat them. Place them on a plate.

Refrigerate the finished truffles for about 30 minutes, then enjoy!