Many of the recipes in the book contain Icelandic sweets that I don't know any good international substitutions for, so I ended up choosing recipes with ingredients where substitutes could be found. This means mostly Síríus Konsúm and Síríus milk chocolate.
These looked promising:
350 g Síríus Konsúm (semi-sweet dark chocolate with a hint of vanilla)
1/2 cup cream
1/2 cup Baileys Irish Cream liqueur
2 egg yolks, at room temperature
1 tbs butter
100 ml icing sugar
Put the chocolate, cream and Baileys in a saucepan and melt together over low heat. Add the egg yolks, one at a time and whisk well between. (I suggest beating the yolks beforehand and then pouring approximately half of the mixture into the chocolate mixture at a time). Remove from heat, stir the butter into the mixture and cool well. Form into balls and roll in icing sugar.