Large quantities! PLEASE DON'T PROCESS IN ONE GO
My choice would be to do this, a little more involved than jds
Chop chocolate spd 9 in three batches remove. Blitz the sugar in batches to icing sugar. Combine eggs and sugar insert butterfly spd 4 for maybe 4/5 mins set aside. Place choc and butter melt 60 4 mins speed 3 check if it is all melted. Add remaining ingredients combine with the spatula and if it needs it combine on speed 3 HTH