Most truffle recipes will use the same technique for making the truffle centers from a flavored ganache. Expect to get messy. A drop cloth comes in very handy. If you are a big fan of dark chocolate, truffle centers rolled in cocoa powder are a delight, but enrobing centers in chocolate ensures that they will travel well and be less messy.
Melt the chocolate.
Chop chocolate into small pieces and melt in a double boiler of hot water. Do not boil the water—melt the chocolate slowly. I usually heat the water until scalding hot and then turn off the heat. Depending on how long it takes to melt the chocolate, you may need to reheat the water. Take your time to avoid overheating the chocolate. Stir the chocolate occasionally to help with melting.
Heat the cream and add to melted chocolate.
While the chocolate is melting, heat the cream over medium heat, stirring frequently until the cream boils. Add any powdered flavorings (e.g. espresso powder) and mix thoroughly. Let the cream mixture cool just a bit from boiling before adding it to the thoroughly melted chocolate. Once you add the cream, the tendency is to think something horrible has gone wrong. Just keep stirring and the cream will slowly disappear into the chocolate. You can use a whisk to blend the cream and chocolate together, but be sure not to incorporate any air into the mixture or else the texture of your truffles could be compromised (less gooey and more dry and crumbly). Wipe the bottom of the double boiler with a towel to remove water and pour ganache into a bowl to cool.
Chill the ganache to firm up.
You can cool the covered bowl at room temperature or even in the fridge, but be sure to stir gently occasionally to prevent the outside from cooling too much before the center. The goal is to get the ganache thick enough to hold a shape but not too thick to pipe with a pastry bag. Little chunks of hardened ganache will clog the tip of your pastry bag. If you are using a small ice cream scoop or teaspoon to create each truffle center, then it is less critical if the ganache cools too much or unevenly. I prefer to pipe my truffle centers with a pastry bag as you can really crank out a lot of truffle centers in a hurry. While the ganache is cooling, clear out some space in your fridge to fit a cookie sheet. The fridge will help firm your truffle centers more quickly.
Method 1: Pastry piping bag.
Once the ganache has thickened sufficiently, fill a large, plastic coated pastry bag equipped with a large (1/4 inch diameter) decorating tip and pipe dollops onto a cookie sheet lined with wax paper. Although you can use a plastic bag for many pastry decorating tasks, you really want a sturdy pastry bag for ganache. You will probably encounter a chunk or two of ganache and you can exert a lot of force on a sturdy pastry bag to expel the reluctant chunk and resume piping. You are going to be rolling the truffle centers later, so worry more about consistency than appearance, but the more spherical the better as you won't have to roll them as much. Fit as many as you can on the cookie sheet and then place the cookie sheet in the fridge to firm them up.
Method 2: Small melon baller.
For this method, you can let the ganache cool as much as you want—cooler is better. Using a melon baller, scoop out small truffle balls and store in airtight container. For smaller batches, this is easier than using a pastry bag. Far larger batches, this is a slower method. In the time it takes you to scoop out and extricate the truffle ball from the melon baller, you can pipe out a half dozen with a pastry bag.
Rolling the truffle centers in cocoa to perfect them.
Once you have made all your truffle centers, clear off some counter space and lay your clean drop cloth or sheet over the counter. Working with cocoa powder can be messy—I would recommend an apron while we are on the subject. I usually set out a plate and pour my cocoa powder in a pile in the center of the plate with my cookie sheet of piped truffle centers on the left and a resealable container lined with wax paper to the right. Thoroughly coat the palms of your hands with cocoa powder and grab a truffle center.
Depending on how firm they are you may need to exert more or less pressure as you roll them to get them to become round. You will need to re-coat your hands with cocoa powder with each truffle center. Keep in mind that the longer you roll them, the more the outside of the truffle center will melt and soak up cocoa powder. Expect to get a thick coating of chocolate buildup on your palms. You will probably need to wash and dry your hands several times. If the truffle centers get too soft before you can get them to a nice round shape, you can make two separate rolling passes. Get them as round as you can and place them in the resealable container. Chill them in the fridge for 20 minutes and you can roll them again. If you did a good job piping tall, spherical dollops, you shouldn't have to make two passes.
Store round centers in airtight container for later dipping or consumption.
Place a piece of wax paper between each layer of rolled truffle centers in your resealable container. This will help keep them from crushing each other. Place them in the fridge and get ready to temper your chocolate. Clean off your counters again, get a clean drop cloth or sheet and remove your truffle centers from the fridge. Let them warm up just a bit as they can cool your melted chocolate interfere with the chocolate temper. Of course, you could also skip tempering and just have a traditional cocoa powder covered truffle. Dark chocolate lovers will love the bitterness of the powder. Dipped truffles travel and keep better, so I tend to dip everything in chocolate.
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