Sables are actually French Shortbread. Shortbreads are traditionally a Christmas cookie made with just four ingredients, butter, sugar, vanilla extract, and flour. They are a rich cookie with a delicate buttery flavor but according to Pierre Herme, the addition of egg whites gives these sables an extremely light and melting texture.
1/2 tsp vanilla powder or the seeds from 1/2 vanilla bean
1 large egg white
Put the butter into the bowl of an electric mixer and beat until creamy. Add the sugar, salt. vanilla, and egg white. Mix for 1 minute, then add the flour. Mix on slow speed only just until the flour is fully incorporated with the other ingredients. This dough is fairly soft and cannot be made with your hands. If you do not have an electric mixer, it is fine to mix the ingredients together with a wooden spoon. Take care not to overmix the dough after adding the flour otherwise these sables will be not crunchy and delicate.
Preheat the oven to 350f(180 c).
Transfer the dough to a pastry bag fitted with a star tip. Pipe the dough in "W" shapes onto a baking sheet lined with parchment paper leaving /4 inch(2 cm) space between each sable.
Bake until light golden, 12 - 15 minutes.