In a small saucepan, gently heat the heavy cream over medium heat until it just begins to simmer.

Remove the saucepan from heat, then add the chopped dark chocolate and optional butter. Stir until smooth.

Stir in the vanilla extract, ensuring it blends well.

Pour the ganache into a bowl and let it cool at room temperature for about 30 minutes.

Cover it with plastic wrap, and refrigerate for 1–2 hours, or until firm enough to scoop.

Use a small cookie scoop to carve out portions of the chilled ganache.

Quickly roll each portion between your palms to create smooth balls.

Roll the truffles in cocoa powder, crushed nuts, or sprinkles until fully coated.

Place the coated truffles on a baking sheet lined with parchment paper and refrigerate for another 30 minutes.

Serve your delectable truffles chilled or at room temperature.