I need you guys to settle an argument that broke out between my father and cousin in law at dinner. My father says biscotti should be made with blanched hazelnuts and my cousin in law says it does not matter if the nuts are skinned. Who is right?
Father-in-law is correct, biscotti "should" be done that way although I have heard it done otherwise. It's just like eating shrimp, they "should" be de-veined when serving to guests but sometimes they aren't.
I guess it's a question of whether you want to be more traditional or not. If the former, then go for blanched nuts.
With un-blanched there's a higher risk of creating a bubble in the biscotti around he nut whereas there's little risk otherwise. Also hazelnut skins can sometimes be somewhat bitter which can contrast with the sweetness you'd expect in the biscotti.
In the end it's a question of preferences.
Personally I like to make mine with almonds and pistachios.