Line a jelly roll pan with parchment or a Silpat. I love my quarter sheet pans for this, but a 9x9-inch square baking pan or something like it will work just fine. Also, you don't have to line it with anything, but it makes for an easier cleanup.
Bring Heavy Cream (1/2 cup) to a boil, keeping an eye on it constantly. Break Bittersweet Chocolate (12 ounce) into small chunks and place in heat-safe bowl. Pour cream over chocolate, push chocolate chunks down with a spatula so they are submerged, and let sit for a minute.
Add Grand Marnier (2 tablespoon), Vanilla Extract (1 teaspoon), and Salt (1 pinch) off the heat, and stir until smooth. Spread mixture into prepared pan, then refrigerate it for about 30 minutes or until almost hard.
Drag a melon baller across firm chocolate mixture to shape the truffles. Drop truffles onto clean baking sheet. Refrigerate truffles for 15 minutes once formed. As you shape, if the chocolate gets too soft, stick the pan back in the fridge for a bit. If it seems too hard, let it sit at room temperature until it is manageable.
Spread some Unsweetened Cocoa Powder (to taste) into a shallow dish, preferably one with sides, If using Powdered Confectioners Sugar (to taste), spread it in a separate dish. Spread truffles into each vessel and shake the vessel to coat the truffles.
Store truffles in fridge or a cool part of your house. Let come to room temperature at least an hour before serving. Enjoy!