In a small, heavy saucepan, bring the heavy whipping cream to a simmer (stir and scrape down the sides with a spatula every few minutes). Then place the chocolate in a separate bowl. Pour the cream over the chocolate, add the vanilla, and allow to stand for a few minutes, then stir until smooth. Allow to cool, then place in the refrigerator for two hours. Remove and with a teaspoon roll out balls of the chocolate preparation. Roll in your hands quickly (so it doesn’t melt) and place on a baking sheet lined with parchment paper. Place in the refrigerator overnight. Finally, roll in cocoa powder with the chopped nuts and serve. If you’re not ready to eat them yet, place the truffles back in the refrigerator until you are ready to enjoy these treats! Depending on the size of each truffle, you may be able to make around 30 to 40 of these nutty chocolate delights.