Place the chopped chocolate and Nutella into a medium-sized, heatproof bowl.
In a small saucepan, heat the cream until it just begins to simmer and then pour it over the chopped chocolate. Let it sit a minute, then gently stir with a wooden spoon until the chocolate has fully melted and the ganache is smooth. Then cover and chill completely to set.
Once the filling is ready to use, melt the remaining chocolate in a microwaveable bowl for 30 seconds at a time (stirring in between) until the chocolate is smooth and fluid.
Using a 1/2 teaspoon measuring spoon, drop it into mini paper cupcake liners spread evenly using a paintbrush.
Allow to harden in the refrigerator for about 10 minutes.
Fill the chocolate covered cups with the filling then brush the rest of the chocolate over the tops of the cups, sprinkle with the hazelnuts and place in the refrigerator to set again (about 15 minutes).