I have a bottle of Amoretti Praline Hazelnut Extract that I've almost used up, which was given to me as a gift. There are other brands of hazelnut extract available on Amazon, or possibly on the baking aisle at Hobby Lobby, Michaels and Joannes. But even without this special (and sometimes pricey) extract, your cookies will be wonderful with just the ground hazelnuts in the dough.