Place 10 oz of the chocolate in a heavy saucepan, and melt over low heat.
Remove the pan from the heat and set aside.
Combine the egg yolks and ½ cup of the confectioner"s sugar in a large bowl, and cream until well blended.
Combine the cream, butter, and remaining ½ cup sugar in a medium-size saucepan and bring to a boil, stirring until the butter and sugar are thoroughly melted.
Slowly pour the hot sugar mixture over the egg yolk mixture, whisking constantly.
Mix thoroughly and set aside to cool slightly.
Then stir in the melted chocolate and the scotch; beat for 1 minute.
Place the mixture in the refrigerator and chill until firm, 30 to 45 minutes.
Meanwhile, place the hazelnuts on a baking sheet and toast them in the oven for 15 minutes.
Remove them from the oven and rub handfuls of nuts in a kitchen towel to remove the skins.
Set them aside.
Roll a spoonful of the chilled chocolate around each hazelnut to form a truffle about 1 inch in diameter.
Set them on a baking sheet lined with waxed paper, and chill thoroughly in the refrigerator 2 to 3 hours.
Melt the remaining 14 oz chocolate in a heavy saucepan over low heat.