PREHEAT OVEN TO 180ºC . Combine the eggs, extract, sugar and salt in a mixing bowl or the bowl of an electric mixer and whip with a hand mixer set at high speed or in a heavy duty mixer fitted with the whip. Continue whipping until the mixture is very light and increased in volume, 6-7 minutes. While the egg mixture is whipping, combine the flour, cornstarch and baking powder and stir to mix. Remove the whipped eggs from the mixer and sift over the flour mixture in three additions, folding it in after each addition with a rubber spatula. The batter will lose most of its air and become rather stiff. Pipe the batter, using a pastry bag with a 2 cm opening, but no tube, onto a jelly roll pan lined with parchment paper or buttered wax paper. Pipe two logs about 4 cm wide and the length of the pan. Bake the logs about 20 minutes, until they are well risen and golden. Remove from oven and place logs on a cutting board to cool about 10 minutes. Using a sharp, serrated knife, slice the logs diagonally at 1 cm intervals. Place the biscotti cut side down on the pan and return them to the oven for about 10-15 minutes, until they color lightly on the cut surfaces. Cool the biscotti on the pans and store them in a tin between layers of wax paper. Makes 48 Cookies