Preparation

• Position a rack in the center of the oven and heat the oven to 350ºF. Line four cookie sheets with nonstick baking liners or parchment paper sprayed with cooking spray. If shaping the tuiles, have a rolling pin at the ready.
• In a medium mixing bowl, combine the egg whites, sugar, and salt. Whisk until blended and a bit foamy, about 1 minute. Add the maple syrup, melted butter, and vanilla and whisk until blended. Add the flour and continue to whisk until smooth and blended.
• Drop the batter by scant tablespoonfuls onto the prepared cookie sheets, positioning them about 4 inches apart (you should be able to fit 4 to 5 to a cookie sheet, but bake only as many as you can drape over your rolling pin, if you plan to shape them). Spread each round of batter into a 4-inch circle with the back of a spoon (use a circular motion to spread the batter outward from the center.)
• Sprinkle about 1/4 tsp. of the walnuts over each cookie. Bake until the cookies are browned around the edges and in spots toward the center, 7 to 9 minutes. The cookies will inevitably be slightly uneven and, therefore, will have a few darker-brown spots. Not to worry —they’ll still taste good. Don’t underbake or the cookies won’t be crisp.
• Working quickly, move the cookie sheet to a rack. Using a metal spatula, lift off the hot cookies one by one and, if shaping, immediately drape them over the rolling pin. Let cool until set, about 1 minute. Carefully remove the tuiles from the rolling pin and set them on a rack to cool completely. If not shaping, immediately transfer them to a rack.