With a sharp knife, chop chocolate into pea-sized chunks, and remove to a medium-sized metal bowl.
In a small saucepan, combine cream, orange zest, and orange liquor and bring just to a boil. Remove from heat immediately. Pour cream mixture over chocolate, stir to combine. Add butter and salt. Stir until mixture is smooth and a ganache forms. Pour into a nonstick cake pan, an 8-inch round or a 12-by-6 inch rectangular pan, and refrigerate for at least an hour, up to three, until the ganache hardens.
When the ganache is ready, use two spoons to begin to shape the ganache into balls. You do this so the truffles will be easier to roll into balls later. The size of the truffles is up to you. Mine are about a third of an ounce each. Place each measured-out truffle on a baking sheet lined with wax paper.
Refrigerate truffles for five to ten minutes, enough time to allow them to firm up again. Meanwhile, fill a large ziplock bag with ice. It’s good to have ice nearby while you roll the truffles, to keep your hands cool and the truffles from melting. With the palms of your (iced) hands, roll each truffle into a smooth ball.
You’ll make a mess, but trust me: this is just about the tidiest method I’ve found, and I’ve tried it all. Remember: spoon, refrigerate, ice, roll. Pour about 1/2 cup unsweetened cocoa powder into a bowl, and roll each truffle in it. This will smooth over any rough edges. You can stop here. They’re done.
Or you can get fancy. You can dip the truffles in more chocolate and top them with candied orange peels. Labor intensive, but never a bad idea. Here’s what you do: In a double boiler, heat another 12 oz dark chocolate, stirring frequently, until just melted. Remove from heat. Add another 2 oz chopped dark chocolate, and stir until the fresh chips melt and the chocolate begins to cool and thicken.
This is called tempering the chocolate. It produces a chocolate that will harden to be snappy and shiny, like all really good chocolate is at room temperature.
If you’re using a candy thermometer, once the chocolate reaches 88 degrees, it’s ready.
With a fork, lower the rolled truffles into the melted chocolate. Lift them out quickly, and allow some of the excess chocolate to drain off the truffle before removing to a baking sheet lined with wax paper.
Sprinkle the dipped truffles with minced candied orange peels, or place a slivered orange peel on top. Your choice! Once the chocolate hardens, you can melt the rough edges down on a warm pan or plate.