In a large mixing bowl, combine the almond flour, sugars, and salt., Add the egg whites and the almond extract, mixing until the dough becomes cohesive., Form the dough into a disk, wrap it in plastic, and refrigerate for at least 1 hour., Preheat the oven to 325°F. Lightly grease a baking sheet, or line it with parchment., Scoop the dough into 1" balls; a teaspoon cookie scoop works well here., Put the extra confectioners' sugar into a shallow bowl. Drop the dough balls into the sugar as you go. Once about five or six are in the bowl, shake and toss the bowl to coat the balls with sugar., Place the dough balls onto the prepared baking sheet, spacing them about 1 1/2" apart. Gently press down on each ball to flatten just slightly., Bake the cookies for 25 to 30 minutes, until they've cracked slightly and are a deep golden brown beneath the sugar, but are still slightly soft when pressed., Remove the cookies from the oven, and allow them to cool for 5 minutes on the pan, then transfer them to a rack to cool completely.