Preheat oven to 350° F. Line a baking sheet with a Silpat baking mat and set aside.
In a small mixing bowl, whisk together the flour, cornstarch and salt. Set aside.
With an electric mixer on medium-high speed, combine the butter and sugar and beat until light and fluffy. With the mixer running on low, slowly add the egg whites and vanilla. Scrape down the sides of the bowl and mix until blended. Add the flour mixture and blend on low until combined.
To form the cookies, drop 2 teaspoons of batter (for each cookie) onto the baking mat. Space each at least 6 inches apart. I baked these cookies two at a time. Using a small off-set spatula, spread the batter into a 5-inch circle taking care to ensure the cookie is evenly thick all the way across.
Bake the cookies for 5 to 7 minutes or until the edges are light golden brown. The center may not look completely set.
Using a thin metal spatula, careful lift the edge of the cookie and roll tightly into a cigar shape. Place the tuile cigar, seem side down, on a wire rack to cool. This may take a little practice but you'll get it! The cookies are hot so work quickly and use your palms to help roll the cookies. If they cool too quickly to roll, place the cookie back in the oven for about 30 seconds then try again. Continue with the remaining batter until all cookies are baked.
Cool completely before dipping if desired.
Place chocolate chips in a small microwave safe bowl and heat on 50% power for 1 minute. Stir the chocolate chips and if needed, microwave again in 30-second intervals until smooth. Dip the end of the tuile into the chocolate and immediately sprinkle with chopped nuts or crushed peppermint. Cool on a parchment lined wire rack until set.
Store in an airtight container at room temperature.