In a medium sized bowl, use a hand mixer or a whisk to mix together 1/4 cup room temperature butter, 1/2 cup icing sugar, and 1/4 tsp vanilla extract until the sugar is creamed into the butter.
Add 1 egg white and whisk into the butter mixture. Add the other egg white, and whisk again.
Slowly add 1/2 cup of flour, whisking add you add the flour. You want to whisk out any clumps of flour so at the end you have a thick batter.
Preheat the oven to 350 degrees F.
Line a baking sheet with a silicone mat. Place a spoonful of batter on the silicone mat, and tap the batter off the spoon. Use the back of the spoon to guide the tuile into a circular shape. The tuile should be approximately 2.5-3" in diameter. Only put about 6 tuiles on the baking mat. You don't want to bake too many at a time, otherwise you won't be able to shape them all when they come out of the oven.
Bake the tuiles for 5-9 minutes. The tuiles are finished baking when the edges start to turn golden brown.
Immediately after removing the tuiles from the oven, use a flipper to remove one of the cookies from the baking sheet.
Shape the cookies by folding it over a metal cone shape, and then place it seam down for it to set. This will create a cone tuile.
To make a "taco" shape, you can drape the cookie over a thick rounded object. You can even use the handle of one of your cookware. Let it sit to dry until it's shaped how you want.
You can make a spiral tuile by making a rectangular shaped tuile. After it's come out of the oven, twist the tuile over a round object. One of the ends will be at the top, the other end should be opposite, and then rolled over the rounded object.
After you're done baking the tuiles, store them in an airtight container.
You can also save the batter by placing it in the fridge covered, and then using it over the next 2 days.