Preheat oven to 325°F. Line cookie sheet with crinkled foil. Beat egg whites and salt until soft peaks form, then gradually add 1 1/2 cups confectioners' sugar and beat until very stiff. Mix the nut meal, flavoring, and 2/3 of the egg mixture. This is the dough for the cookies. Let it rest in the fridge 1 hour. Sprinkle confectioners' sugar on wax paper, add dough, sprinkle with more sugar, and top with another piece of wax paper. Roll to 1/4-inch thick. Peel off the top paper, sprinkle more sugar, reset paper, flip, and peel off the second paper. This ensures the cookies won't stick. Using cookie cutters (or a knife), cut shapes into the dough. If it is too sticky, dip the cutters in confectioner's sugar. Re-roll scraps. Bake 10 minutes. Using a very small piping tip (or a knife to spread), pipe the remaining egg white on top and bake another 5 minutes. Cool on a rack.