Hazelnuts

I'm going to be using hazelnuts in a Imperial stout I'm making. How should I brew with them to extract the most flavor?

I was thinking of crushing / roasting and then using them in my mash. Would this work?

I think putting them in the mash is the general recommendation when people want to use actual nuts in the beer.

There are a lot of hazelnut recipes that just use the extract at bottling time - might be worth looking into.

You'll probably get a lot of people who will complain about loss of head retention due to the fats in the nuts. They are definitely correct, but my opinion is who cares? Head retention is overrated. Nice, but not necessary. I would rather sacrifice head retention to make a hazelnut beer that tasted like hazelnuts.

I can't see why that wouldn't work. The roasting would bring out the hazelnut oils and that would be passed in to the wort. I have no idea on how much hazelnuts you would need though. It may be easier to gauge the the proper amount using an extract. Less trial and error.