Place the finely chopped dark chocolate in a heatproof bowl.
In a saucepan, heat the heavy cream over medium heat until it just begins to simmer. Remove from heat immediately.
Pour the hot cream over the chopped chocolate. Let it sit undisturbed for a minute to allow the chocolate to soften.
Gently stir the mixture using a spatula or whisk until the chocolate is completely melted and the mixture is smooth and glossy. If there are any remaining lumps, gently heat the mixture over a double boiler or in short bursts in the microwave, stirring frequently, until fully melted.
Cover the bowl with plastic wrap and refrigerate for at least 2 hours or until the mixture is firm enough to handle.
Once chilled and firm, remove the chocolate mixture from the refrigerator. Using a teaspoon or a melon baller, scoop small portions of the mixture and roll them into smooth balls between your palms. Place the truffles on a parchment-lined baking sheet.
If desired, roll the truffles in cocoa powder or other desired toppings, such as melted chocolate, crushed nuts, shredded coconut, cocoa nibs, or sprinkles. Place them back on the baking sheet.
Once all the truffles are coated, return them to the refrigerator for about 30 minutes to set.
Store the dark chocolate truffles in an airtight container in the refrigerator until ready to serve. Allow them to sit at room temperature for a few minutes before serving to enhance the flavors.
