Preheat oven to 350°. Line two baking sheets with parchment or non-stick baking mats.
Finely chop hazelnuts in a food processor or by hand, if using whole. Set aside.
In an upright mixer or using a hand mixer, begin whipping egg whites on medium speed. As they begin to get bubbly and foamy, add in the extracts and salt. Increase mixer speed to high and continue beating until eggs white turn solid white. Begin adding sugar in, one Tablespoon at a time in fairly quick succession, until all the sugar is added.
Continue whipping egg whites until they are very stiff and hold stiff peaks, and the sugar is completely dissolved into them. (Rub a little of the mixture between your fingers to feel if the sugar is dissolved.
Using a spatula, gently but thoroughly fold the hazelnuts into the egg whites in three batches. The mixture will become a little stiff at the end-- that's OK.
Using a one Tablespoon scoop or spoon, drop the batter into the baking sheets. With lightly damp fingers, gently pat the tops of the cookies down. (They will not spread as they bake.) Bake for 12-15 minutes until golden around the edges and on the bottom. Cool on baking sheets.
These will keep in a sealed container for several days, and freeze well.