1. Line three baking sheets with Silpat baking mats.

2. Grind almonds with granulated sugar in the bowl of a food processor until fine. Transfer to a medium bowl. In the bowl of an electric mixer fitted with the whisk attachment, beat egg whites until stiff peaks form. Add almond extract. Gently stir egg-white mixture into almond mixture to form a thick paste.

3. Drop dough in rounded teaspoons onto prepared baking sheets about 1 1/2 inches apart. Dust with confectioners' sugar, and let stand at room temperature to dry for 2 hours.

4. Place rack in center of oven, and preheat oven to 300 degrees. Transfer sheets to oven, and bake amaretti until edges are golden and cookies are firm, 20 to 25 minutes. Transfer cookies to a wire rack to cool. Dust with confectioners' sugar. Repeat with remaining cookie dough.