Wanting to make decadent liqueur-based sweet treats for my friends, I scoured high and low for recipes. This little gem came from the most unlikely place, but it fit the bill perfectly. Stunningly simply, utterly moorish :-)
Break chocolate up and place in a bowl with the brandy. Place bowl over a saucepan of simmering water. Stir gently to combine until the chocolate is smooth.
Stir in the butter and egg yolk until well combined (the heat from the chocolate will help melt the butter).
Refrigerate until firm enough to shape into balls - I made mine slightly larger than standard marbles, but it's up to you and your conscience! Roll each ball in the cocoa (or you could experiment with chocolate hail, crushed pistachio nuts, etc. I used drinking chocolate, as it's sweeter than plain cocoa).
Return to the fridge (or freeze, as desired). Serve chilled.