Obtain 1 pound of dark chocolate and 1 cup heavy whipping cream. Be sure to select a chocolate that you enjoy the flavor of.
Cut the chocolate into pieces using a large serrated knife (like a sturdy bread knife). Cutting the chocolate into strips about 5 mm apart with the serrated knife will cause the chocolate to break into small pieces. Pieces of chocolate will fall all over the place, so I like to place the cutting board in a sheet pan to catch the chocolate shards.
After breaking down the whole pound of chocolate, you should have a bunch of similarly sized pieces. Small, uniformly sized pieces will make melting the chocolate evenly easier. Pour all the pieces into a medium heat proof bowl.
Bring the cup of heavy whipping cream just to a boil. (This is called scalding.)
Pour the scalded heavy cream onto the chocolate and allow it to sit for five minutes.
Stir the now melted chocolate with the cream. Chocolate and small amounts of aqueous solutions (liquids containing water) do not mix well - the chocolate clumps up in what is called seizing. However, when a substantial amount of liquid is added to the chocolate, we can make chocolate syrup. A ganache is simply a syrup of chocolate and cream that does not contain enough cream to be liquid at room temperature. Once this mixture cools, it will form a hard ganache that can be molded into shapes.
The melted ganache should be smooth in texture without lumps. If not all the chocolate has melted, you can heat the ganache gently over a hot pot of water. Stir until the chocolate melts and the ganache is smooth.
You can transfer the ganache into a smaller bowl to cool. When the ganache is solid, it may be easier for you to scoop out when working with a smaller bowl. Let the ganache cool down and chill for about an hour in the refrigerator to harden. Cold ganache is harder to scoop, but easier to form into a ball.
Using a melon baller or small ice cream scoop (such as a #70), scoop out balls of hard ganache and place on a cookie sheet lined with either parchment paper or a silicone baking mat. As the ganache gets warmer, it will have a tendency to stick to the scooping device. You might find it easier to work with after rechilling the ganache, dipping the utensil in ice water, or simply using your hands to form rough spheres.
After forming all the balls, chill the pan in the refrigerator for fifteen minutes to allow the ganache to harden back up and set into their shapes.
Scoop a little cocoa powder into a small bowl. Use a pair of spoons to pick up and roll each ganache ball in the cocoa powder to coat.
If you prefer a hard chocolate shell, then you'll need to melt and temper some chocolate (usually, a couple ounces will be more than enough to coat the truffles). Once the chocolate has been tempered, use a spatula to spread some onto the palm of one hand. Place the ball of ganache into the layer of chocolate and rotate, coating the ball. Place the truffle on a sheet of parchment paper or silicone baking mat or other nonstick surface for it to cool and set. Repeat the spreading of chocolate on the palm and coating for each truffle. The tempered chocolate will shrink slightly as it cools and clad itself to the ganache. Because of this shrinking action, if it cools too rapidly, the shell can crack, so don't immediately chill them in the refrigerator - allow the truffles to set in a cool room. The ganache should also be allowed to warm up a bit before you coat them. After the chocolate has hardened, chill for 15 minutes in the refrigerator and then remove and store at room temperature. The chocolate coated truffles should not be allowed to touch each other (touching the truffles together can mar the hard surface of the truffles) - so divide them with small paper cups or paper muffin liners.
The cocoa dusted truffles can be packed together without harm. These truffles can be stored at cool room temperature in an airtight container for at least a month - but good luck keeping them from being eaten for that long!
Also you can buy some inexpensive molding sheet instead of scooping you can use this.
thnx to Michael Chun