Roast the hazelnuts in one layer on a jellyroll pan at 350 degrees for about 15 minutes. Allow them to cool slightly, then rub them in a towel to loosen and remove the skins. After removing the hazelnuts from the oven, lower the temperature to 250 degrees; set racks at the upper and lower thirds. Crush the hazelnuts coarsely with the bottom of a saucepan.