Place the finely chopped chocolate in a medium heat-proof bowl.
In a small saucepan over medium heat, bring the heavy cream to a gentle simmer. Do not let it reach a rapid, rolling boil.
Pour the hot cream over the chocolate and let it sit undisturbed for 2 minutes to allow the chocolate to soften.
Using a silicone spatula, gently stir the mixture in small circles starting from the center until it becomes a glossy, smooth ganache.
Fold in the hazelnut cocoa spread and vanilla extract until the mixture is uniform in color and texture.
Cover the bowl with plastic wrap, pressing it directly onto the surface of the ganache, and refrigerate for 1.5 to 2 hours, or until firm enough to scoop.
Using a small cookie scoop, portion the ganache into uniform balls and place them on the parchment-lined baking sheet.
Roll each ball between your palms quickly to smooth the shape, then roll them in either the chopped hazelnuts or cocoa powder.
Keep the finished truffles chilled until you are ready to serve them.