Before the freezing time is up for the truffles you are going to chocolate coat, prepare all your decorations like crushing/roughly chopping nuts, and having any sprinkles you want to use, all ready in small bowls or plates. If you want to be super precise you can use crafting tweezers, to help position sprinkles if only using a few. Have baking/parchment paper ready to sit the truffles on when wet (again on top of plates or trays to go in the fridge this time). You can place directly in little petit four paper cases (or mini muffin cases) if you like, or do after set. (If you make the cake truffles bigger, small fairy cake paper cases might work. But cases are not essential). Also break up the chocolate, and melt in the microwave, in 30-second bursts, mixing in-between each time. (Don't do any longer than 30 seconds or you run the risk of burning the chocolate). Alternatively, melt the chocolate in a bain-marie (heat-safe bowl on top of a pan of barely simmering water, where the bottom of the bowl doesn't touch the water). See notes for more tips of melting chocolate.
Once ready to do the coating, take about 1/3 of the frozen cake truffles from the freezer (don't take all out at once as it makes dipping harder). Then to coat the cake balls, simply take one, and place in the melted chocolate, and use a small spoon to move the ball gently to turn so all is coated. You can also use a second spoon to drip over if needed.
Then carefully transfer the coated cake ball on to the prepared paper-lined plate or tray, by using a fork (small forks are best). Scoop under the cake ball to lift it, and use another fork or butter knife, to gently push the cake off the fork, making it slide onto the paper.
Immediately add on any chopped nuts or sprinkles now, to the top of the wet chocolate coated truffles. If you want to completely coat in sprinkles or nuts, this is harder. I suggest waiting a few seconds, and then lifting the cake truffle with the same fork, and turn the cake ball over onto the bowl of sprinkles, letting the topmost part of the cake hit the sprinkles first. Then gently push the cake ball to coat more. And add more sprinkles by hand if need be, before transferring back to the paper to set.
Repeat the chocolate dipping and decorating process, one cake truffle at a time. The dark/bitter chocolate will take longer to melt and I was not a lover of white chocolate, but it melts so easily, and quicker and was much easier to dip in. And tasted great with the cake truffle filling. In the end I really was happier with just chocolate coated, or with a simple small decoration on top. They look more professional.
Once all coated, place the plates in the fridge for about 30 minutes, to set up completely.