If the almonds are not peeled, toss them into boiling water for a minute, run them under cold water, strain them and blot them with paper towels. Squeeze the nuts so the skins come off easily. Lay them out to dry or dry them for a few minutes in the oven at 300°F (148° C);
If you have bought peeled almonds, put them in a food processor and pulse them along with the sugar. Place the ground mixture in a bowl.
Beat the egg whites until firm (the test for firmness is to turn the bowl upside down, and if they don’t fall out, they are beaten enough); gently fold in the sugar, the almond mixture, and the almond extract to make a smooth paste;
Place some parchment paper onto a baking tray, use a pastry bag with a sized-10 tip (0.4 inches) to place walnut-size dollops of the mixture approximately 1 inch (2cm) apart; let sit for 1 hour;
Preheat the oven to 300°F (148° C) and bake for 30 minutes, or until they are golden brown;
Open the door, switch the fan on, and let amaretti cool down in the oven so that any trace of leftover moisture is eliminated, and your cookies get really crunchy.