Preheat oven to 350° F. Position rack in the center.
Line baking sheet or loaf pans with parchment paper.
In a medium bowl, sift flour. Set aside.
In a large mixing bowl, or bowl of electric mixer fitted with whisk attachment beat the yolks.
Add the sugar. Whisk together.
Add vanilla extract.
Switch to paddle attachment. Add flour to egg mixture and incorporate. Mixture will look like bread crumbs.
With wooden spoon, incorporate the almonds. Set aside.
In a large mixing bowl, or bowl of electric mixer fitted with whisk attachment beat the egg whites with a pinch of salt until they reach the stiff peak stage.
Fold whites in flour and nut mixture.
Divide dough into quarters. Place each quarter on the cookie sheet, shaping into a log. I find it easier if my hands are slightly moistened with water. Alternatively, divide dough in half and place in loaf pans. (9.25x5.25x2.75)
Bake for approximately 15 - 20 minutes or until firm to the touch (will take a little longer in the loaf pans).
Remove from oven, wrap in clean dish towels and allow to cool down.
Once cool, transfer loaves to cutting board.
Using a serrated knife, slice cookies about 1/8 inch thick (or thinner).
Place slices on the baking sheets, and bake for about another 10-15 minutes (the longer they stay in the oven, the crispier they get).
Can be stored at room temperature for a few weeks...if they last that long.
In order to toast the almonds, start by preheating the oven to 325° F. Position rack in the center. Spread almonds on a baking sheet and toast in oven for about 12-15 minutes. Almonds must be cool before using them in the recipe. Almonds can be replaced by pistachios. No need to toast.Please keep in mind that the nutritional information provided below is just a rough estimate and variations can occur depending on the specific ingredients used.