- 2 large egg whites, at room temperature 30 minutes
- 1/2 stick unsalted butter, softened
- 1/2 cup sugar
- 6 tablespoons all-purpose flour
- 1/4 teaspoon pure vanilla extract
- 1/8 teaspoon salt
- 3 ounces sliced almonds (1 cup), toasted and cooled
- Equipment: a 17- by 11-inch nonstick bakeware liner such as Silpat
- Preheat oven to 350°F with rack in middle.
- Blend together egg whites, butter, sugar, flour, vanilla, and salt in a food processor just until smooth.
- Put liner on a baking sheet. Using 2 teaspoons batter per cookie, make 6 mounds, spacing them 3 inches apart, then spread into 4 1/2- to 5-inch rounds with back of a spoon (they will be very thin but try to spread batter as evenly as possible). Sprinkle each round with about 1/2 tablespoon almonds.
- Bake cookies until golden-brown, 7 to 9 minutes. Let stand on baking sheet 1 minute, then, working quickly, remove each cookie with a metal spatula and drape over a rolling pin or a wine bottle (you will need 2 pins or bottles) to form a curved shape. Let stand until crisp, about 20 minutes, then transfer to a rack to cool completely.
- Cool liner and baking sheet before making more cookies.