Pre-heat the oven to 350°F. Line two baking sheets with parchment paper.

Crumble the almond paste in the bowl of a food processor. Pulse until the almond paste is broken up into coarse crumbles. Add the sugar and process until the sugar is incorporated into the almond paste. Add the egg whites, salt and orange zest and process until the dough is smooth.

Place the pine nuts on a small plate. Roll the dough into balls about 1½ tablespoons in size. Roll the top and sides of the ball into the pine nuts, leaving the bottom of the ball uncovered with nuts. Place the dough balls, nut sides up, three inches apart on the parchment paper and transfer the baking sheets to the oven.

Bake for 13 to 15 minutes. The cookies should be lightly browned and soft to the touch. Cool on the baking sheet for 5 minutes and then transfer the cookies to a cooling rack.

When cookies are completely cooled, dust lightly with powdered sugar if desired.

Store in an airtight container for up to one week, or freeze (without the powdered sugar) for up to 3 months.