Ingredients

• 5 tablespoons unsalted butter, room temperature
• 1 cup powdered sugar
• 2 large egg whites
• 1/2 teaspoon vanilla extract
• 1/2 cup all purpose flour

Instructions

1. Using electric mixer, beat 3 tablespoons butter and sugar in medium bowl until coarse meal forms. Beat in egg whites, 1 at a time, then vanilla. Add flour and beat until well blended. Melt remaining 2 tablespoons butter in small saucepan over low heat. Mix warm butter into batter.
2. Position rack in center of oven and preheat to 350°F. Lightly butter 2 nonstick baking sheets. Spoon 1 heaping teaspoonful batter for each cookie onto sheets, spacing 4 inches apart and forming 3 cookies on each sheet. Using small metal offset spatula or back of spoon, spread batter for each cookie to very thin 4-inch round. Bake cookies on 1 sheet until 3/4 inch of edge is golden brown, about 5 minutes. Run thin flexible spatula under edge of 1 cookie to loosen and remove from sheet. Working quickly while cookies are still warm and flexible, roll 1 cookie around handle of wooden spoon into cylinder. Slide cookie onto work surface. Shape remaining cookies into cylinders, returning sheet to oven briefly to soften cookies if necessary.
3. Bake cookies on second sheet while first baking sheet cools. Repeat with remaining batter, using cool baking sheet each time. Cool rolled cookies completely. (Can be made 1 day ahead. Store airtight at room temperature.)