Heat the heavy cream
in a 2-quart heavy-bottomed saucepan until bubbles begin to form around the edge of the pan. Make sure that you have chopped the chocolate as finely as possible to allow it to melt quickly and easily. Place the chopped chocolate in a medium-size mixing bowl. Make a ganache by pouring about half of the hot cream over the chocolate and letting it sit for 30 seconds to melt
the chocolate. Then slowly whisk until smooth and homogenous. Do not add all of the hot cream to the cold chocolate at once; the shock of the temperature extremes would cause the fat in the chocolate to separate.
Pour the ganache onto a plastic wrap-covered baking sheet and spread evenly with a rubber spatula
. Cover the ganache with plastic wrap
and allow it to cool for at least 4 hours at room temperature.
When the ganache has cooled to the consistency of a thick paste, scrape it into a pastry bag
fitted with a 1/2-inch plain tip. Pipe 1-inch-diameter mounds spaced 1-inch apart on a parchment paper-covered baking sheet. To pipe the mounds, hold the pastry bag at a slight angle and allow the tip to touch the parchment as you begin to pipe. Once you have formed the mound, stop squeezing and lift the tip straight up
, leaving a small tail on the top of each mound. You can also use a spoon and drop small mounds of ganache
onto the baking sheet. Let the truffles harden in the refrigerator for 15 minutes, until they are hard enough to roll with your hands.
To roll the mound into a ball, place a truffle
between both palms, squeeze slightly and roll between your hands. The truffles will look nicer if they are as round as possible.
When all the truffles are rolled into balls, they are ready to be coated. If they have become too soft, place them in the refrigerator for 1 to 2 hours until they are firm enough to coat. Roll in cocoa powder or chopped walnuts
, one at a time.