Preheat oven 325F. Line baking sheet with silicone baking mat or parchment paper.

In a small mixing bowl, beat egg white, salt, vanilla extract and sugar until foamy. Whisk until sugar is completely dissolved. Whisk in flour until no lumps. Then, gently fold in almond slices and butter.

Spoon 1 tablespoon of batter onto prepared baking sheet and spread batter into a 2 to 3-inch circle. (I used a little offset spatula to spread them.) Make sure the almonds flakes are not overlapping. Spoon the rest of the batter on baking sheet with each cookie at least 1-inch apart. (I was able to cook about 9 per tray.)

Bake 9 to 12 minutes depending on their size, rotate baking sheet once during baking. Bake until slightly golden brown. Remove from baking sheet and cool completely on wire rack. Cookies will crisp up once completely cool.