In an electric mixer fitted with the paddle attachment, beat the butter at medium speed until creamy, about 30 seconds. Add the confectioners' sugar and flour and mix until combined. Add the egg whites one at a time, beating after each addition just until well blended, about 1 minute in all. Refrigerate the batter for 30 minutes.
Preheat the oven to 350 degrees F. Have a rolling pin at hand. Spray a baking sheet with nonstick cooking spray or line it with parchment paper.
Spoon 2 teaspoons of the batter onto the baking sheet and with a small, offset metal spatula, spread it evenly into a 3-inch circle. Repeat to form more tuiles, baking only 6 to 8 at a time. Refrigerate the remaining batter while you bake the tuiles.
Bake the tuiles for 4 to 6 minutes, until lightly browned around the edges. Remove from the oven and immediately shape the tuiles, lifting up each one with a metal spatula and draping it over the rolling pin so it curves, just until set. Repeat with the remaining batter. Store the tuiles in a cool dry place in an airtight container for up to 1 week.
Courtesy of Simply Sensational Desserts, Francois Payard, Broadway Books/Random House, 1999