Combine heavy cream and coffee granules in small mixing bowl. Make sure you use
heavy whipping cream, not just "whipping cream," and add coffee to taste.
Stir until dissolved, about 5 minutes.
Add Nutella. Beat with electric mixer on
medium speed for 1 minute. Stop mixer, scrape sides and bottom of bowl, and continue
beating on medium just until beaters leave impression (very soft peaks), about 1
minute. (Mousse will seem too soft, but will stiffen when chilled.)
into individual serving dishes, and chill (at least 4 hours).
If desired, top with whipped cream just before serving.