Melt the dark chocolate in a double boiler. As it melts, add the butter slowly and mix in
Take it off the heat and mix in the egg yolks, icing sugar and vanilla extract
Let it cool completely, then put in the fridge overnight to set
The next day set up the coatings of your choice by pouring them onto greaseproof paper or into bowls
Set out some petit four cases to hold the truffles in
Scoop out the mixture with a spoon and roll it between the palms of yours hands, then roll it in the various coatings until covered
Repeat until the truffle mixture is all used
If you let the mixture cool in a square tray you can cut it into squares if you don't want to roll them
Store in the fridge and eat within 2 weeks