In large bowl, combine Nutella, mascarpone and hazelnut liquor
Whisk at high speed until fully combined and fluffy
Place in refrigerator to chill while making whipped cream
Put heavy cream in a separate bowl and start whisking on low speed until it just begins to set
Increase speed to medium high until soft peaks begin to form
Add cocoa powder and confectionary sugar and whisk on low at low speed until just combined
Increase speed to high and beat until cream just holds firm peaks.
Return Nutella mascarpone mixture to the mixer. Add about one quarter of the whipped cream to the Nutella mascarpone mixture and whisk to lighten
Fold in remaining whipped cream until well combined.
Place in serving cups and top with chopped hazelnuts and/or shaved chocolate if desired
Notes
It is important to keep everything cold throughout the process. Bowls, whisks, cream, mascarpone. The only thing to keep room temperature is the Nutella (until its whisked into the mascarpone). Put my work bowls and whisks in the freezer about 15 minutes before you begin working.