Add the almond flour, 1 ½ cups powdered sugar and ¼ teaspoon salt to the bowl of a food processor fitted with its blade. Use a spoon to stir the ingredients a bit.
Pulse the almond flour mixture briefly to combine further. Stop the machine to scrape down the sides with a plastic spatula as needed.
Separate the egg white from a large egg. (Store the yolk in the refrigerator for another use.) Add the egg white and almond extract to the food processor bowl. Pulse the machine again until the almond paste comes together in a ball.
Make the Dough
Use a wooden spoon to break up the almond paste into pieces in the food processor. Add the granulated sugar and run the processor until crumbs form.
Add the two egg whites. Process just until combined.
Freeze the dough for 20 minutes so it will be easier to roll. Preheat the oven to 350 degrees F.
Assemble & Bake
Line two half-sheet pans with parchment paper and have a little bowl of pignoli nuts ready. Roll the chilled dough into 1 ½-inch wide balls. Dip the tops and sides of the balls into the pignoli nuts and place the balls on the prepared pans, spaced a couple of inches apart. You should be able to fit a dozen on each pan.
If at any point, the dough becomes too soft and sticky to work with, place it back in the freezer for a few minutes, then continue rolling.
Bake one pan at a time on the center rack of the oven for 15-16 minutes, or until the pignoli cookies are golden brown. Remove the pan from the oven and let the cookies rest for five minutes to set. Then, transfer them with a spatula to a cooling rack. Dust on powdered sugar, if desired.
Store the cookies at room temperature for up to four days in a sealed plastic container with wax paper separating the layers. You also can freeze the cookies (without powdered sugar dusting) and use them within a month for best quality.
Notes
If you don't have a food processor:
You can stir the almond paste ingredients with a wooden spoon in a mixing bowl to combine them into a paste.
When making the dough, break up the paste with the spoon and use a pastry cutter to cut in the sugar until crumbly.
Add the egg whites and use a hand mixer to combine everything into a dough.
Don't bake the cookies on a silicone baking mat, because the dough is too sticky and will get stuck in the tiny holes. If you don't have parchment paper, you can lightly grease the pan with cooking spray. You can make the almond paste weeks or months ahead of time, shape it into a log and double-wrap it in plastic. Store the almond paste in the refrigerator for up to a month or in the freezer (use a freezer bag) for up to three months. Let it come to room temperature before using it.