In a medium saucepan, bring 1/2 cup heavy whipping cream to a low simmer, whisking constantly. Add chocolate and allow it to melt completely. Place the remaining 1 cup of heavy cream into a medium mixing bowl and whisk vigorously by hand (or with an electric mixer)until soft peaks emerge. Reserve, 1/2 cup for topping, cover and transfer to the refrigerator. Continue to whip the remaining cream until stiff peaks emerge.
Fold the cream into the chocolate mixture, working quickly until everything is incorporated. Transfer to serving vessels and refrigerate for 1-2 hours until firm.
Serve topped with reserved whipped cream and chocolate flakes or chopped nuts.