Honestly, I used boxed cake mix with this recipe because I was in a hurry and my kids wanted these asap. 

Prepare cupcakes according to the package directions. Bake, and cool.

While cupcakes are cooling you can prepare the frosting and Ganache.

For the Chocolate Ganache:

¾ cup semi sweet chocolate ( I used chocolate chips)

½ cup heavy cream

1 tsp. Light corn syrup( Karo Syrup)

Place chocolate into medium bowl and set aside.  Heat cream in a saucepan over medium-high heat just until it starts to simmer.  Remove from heat and pour over chocolate. Let sit for about 5 minutes and then stir with a wooden spoon until chocolate is completely melted and smooth.  Stir in corn syrup. Allow to semi cool.

For the Chocolate Hazelnut Swiss Meringue Buttercream: 

2 cups unsalted butter, at room temperature
5 egg whites, at room temperature
1 cup sugar
¼ tsp. salt
1 ½  tsp.vanilla extract

¼ cup cocoa powder
¾ cup Nutella or any hazelnut spread 

In bowl of stand mixer combine egg whites, sugar and salt.  Place over a pan of simmering water or double boiler and whisk continuously until temperature reaches 160 on a candy thermometer and the sugar is dissolved, about 3 minutes. (The mixture should feel smooth when rubbed between your fingers not grainy).

Attach bowl to mixer fitted with the whisk attachment.  Starting on low speed and gradually increasing to medium-high, whisk until stiff peaks form and mixture is fluffy and glossy, about 10 minutes.  Your bowl should no longer feel warm to the touch.

With mixer on medium speed, add butter a few tablespoons at a time, mixing well after each addition.  Continue mixing until icing is smooth and silky, about 10 – 15 minutes.

Add vanilla extract, cocoa powder, and hazelnut spread.  Mix until well combined.

For assembly:

¾ cup toasted and chopped hazelnuts

Ferror Rocher chocolate candies

Pour hazelnuts into a small bowl.  Dip tops of cupcakes into dark chocolate ganache, letting excess drip off.  Gently roll cupcake in the chopped hazelnuts, covering exterior edge with nuts but leaving center uncoated.  Using a pastry bag fitted with a star tip, swirl on a mound of hazelnut buttercream frosting. Put into the refrigerator for about 10 minutes or until your frosting is firm.  Then drizzle on more ganache and top with a Ferror Rocher. Store in refrigerator until ready to serve. You can take them out about 10minutes before serving. Best enjoyed at room temperature.