Preheat oven to 375°F. Line baking sheets with parchment
Place pecans and sugar in the bowl of a food processor and process until finely ground.
With the processor running, add vanilla extract and egg whites, and let machine run until a batter forms and rides up on the blades.
Transfer cookie batter to a piping bag fitted with a 3/8 inch tip.
Pipe batter into 1 1/2 inch rounds, leaving an inch of space between cookies. Lightly press down tips with a dampened finger.
Bake for 18-20 minutes, rotating sheets from top to bottom and front to back halfway through. The cookies should be lightly browned along the edges.
Let cool completely before removing from parchment and storing in an airtight container.
