7 oz. (14 oz.) chocolate chips
~1 T oil
--OR--candy melting pellets (try Michael's); Wilton is the standard brand.
Beat butter and sugars until fluffy; several minutes (watch that your mixer doesn't overheat). Add milk, vanilla, salt, baking soda & mix. Gradually add flour. Add chips & mix. This will be a fairly stiff dough; stiffer than you'd make cookies from.
Chill dough 1 hour. Form into balls (~1" to 1 1/2" in diameter). You may have to re-chill the dough. It's very difficult to work with this dough when it becomes sticky and gooey.
Freeze on waxed paper-lined cookie sheet. You want to work with frozen truffles, not just chilled ones, because the coating will be hot.
Melt chocolate chips/pellets. I use my WV and watch carefully. You don't want the chocolate to burn (it will look crumbly and smell "off" when this happens). 15 seconds the first time; stir. Then 6-10 seconds for remaining time. Stirring will speed up melting. Don't expect a liquid puddle. Just pretty runny. You may need to add some more oil, even to the pellets. You'll have a good feel for this after you dip your first truffle. If you add more oil, give it a little zap and stir again. Start with about 1/2 t. You can always add more.
Dip truffles in chocolate and let cool on [same] waxed paper-lined cookie sheet. Use a fork. Remove excess chocolate by "wiping" the utensil across the rim of the bowl.
They also make a "dipping spoon," which looks like an oval ring on a handle; like a dipper for Easter eggs. These are very handy. If you think you might be doing this a time or two, look into getting one of these gadgets. There are elaborate and expensive sets of dipping utensils (including some that look like forks), but I've been perfectly happy with my plastic "Easter egg" type. Don't see why you couldn't make one out of wire, actually. Or, shop for some plastic ones by Wilton. (They're about $3 these days. March, 2010.) There are many recipes on the Web for other centers, such as peanut butter, etc.
UPDATE: Octover, 2011. I have found a very cheap and readily-available utensil for dipping! You can find one, too! Go to your local hardware store and buy a paint can opener, the kind with the bent "screwdriver" tip on one end for opening the can...and a truffle-dipping loop on the other (some people use it for a bottle opener, but I know it's for dipping truffles). Wash very well; I ran mine through the dishwasher twice, retrieving it after the cycle was done and drying it thoroughly; it is made of steel and will rust. Works well; cheap; easy to find! Can't beat that!
Make sure all parts of the truffle are covered by chocolate so the interior doesn't dry out in the refrig. They also look better. You may have to "dab" on the uncovered parts (and the folk holes) with a toothpick dipped in chocolate. (Avoiding holes is why a dipping spoon is helpful.)
If the truffles get soft while you're dipping, chill them.
When the chocolate gets cool, give it a little zap. Watch! You don't want it to burn! You will have to reheat the chocolate at least once, as dipping is a slow process. The cooler and thicker the chocolate becomes, the harder it is to work with. With a full batch, you'll probably have to reheat several times. You may need a dribble of oil each time you reheat.
If you need more chocolate, throw in some of the mini chips. If you have leftovers (likely), drop it in clumps on the cookie sheet, maybe mixing in some chopped nuts first.
Freeze truffles again, then move to a waxed-paper lined container, using waxed paper between layers. Keep chilled until you're ready to put them on a serving plate. Should be out of the refrigerator about 1 hr before serving.
Half a recipe makes about 2 dozen.