Place the chocolate in a stainless steel bowl, over a pot of simmering water, stir with a rubber spatula as the chocolate melts, if the pan starts to get too hot, remove it from the heat.
Continue to stir the chocolate until it has melted completely, then remove from the heat.
Cut the butter into 8 pieces and mix it into the melted chocolate until it has been completely absorbed by the chocolate.
Set the chocolate aside to cool to room temperature
add the egg yolks to the bowl of your mixer and begin to whip them until doubled in size, then begin to slowly pour the sugar in a steady stream into the yolks. Continue to whip for another minute.
add the liquid to the egg yolk mixture and place your mixing bowl over a pot of simmering water and whisk the yolk mixture until it becomes very thick.
When the egg yolks have thickened, continue to whip in your stand mixer until the mixture has cooled.
when the sabayon has cooled, fold it into the chocolate mixture until well blended.
Whip the cream in your stand mixer until it holds its shape, then fold it into the chocolate mixture.
Cover with plastic wrap and refrigerate until set.