Staff encouraged me to write to Princess Cruise Lines for the recipe however I never received a response. Hazelnut is one of the ice cream flavors served for dessert at the dining room, supposedly made on board.
I'd love to have the recipe.
I would guess that they use a product called gianduja(pronounced john-du-ya) which is a blend of milk or dark chocolate and roasted hazelnuts.
It has the consistance of peanut butter and just melts in your mouth. We use this product when making a hazelnut belgian chocolate mixing the gianduja with cream and chocolate to make a delicious melt in your mouth center. You can buy it in fine chocolate stores.
If you have the princess cookbook on page 218 I would experiment with the chocolate rum ice cream and use gianduja in place of the chocolate and instead of the rum use frangelico or replace it with another 1/4 cup of milk or cream.
Princess does make all of their Ice Cream on board ship! I'm not sure which address you checked into but try this: 24200 Magic Mountain Parkway, Santa Clarita, CA 91355-1283
Caribbean Princess Jan 07 2007
Sun Princess May 2006
Island Princess Mar-2005
Royal Caribbean Grander of the Sea 2000
Star Princess (Old)-1997