In a food processor, blend almonds until they are small pieces (not too fine). Place in a bowl. Add egg whites and brown sugar. Refrigerate batter for 30 minutes.
Preheat oven to 350°F. Line a baking sheet with parchment paper.
Scoop onto prepared baking sheet. They spread so don’t place them too close together. Bake at 350°F for 15 minutes. Let cool. Optionally, you can sprinkle these with confectioners’ sugar once they’re cool (we didn’t).