1stick (4 oz)unsalted butter, , at room temperature (on the colder side rather than warmer though!)
1/2cup (100g)white sugar
2egg whites, (from 2 large eggs; 60g)
1/2teaspoonvanilla extract
zest of 1lemon , (Meyer lemon is a fun add here and often available during the winter season)
optional: zest of 1/2grapefruit
1/2teaspoondiamond kosher salt (if using any other salt, use half the amount)
3/4cup (90g)all purpose flour
Instructions
Preheat oven to 350.
In the bowl of a standing mixer or large mixing bowl, add sugar, butter, and lemon zest (and grapefruit zest if you using). Using paddle attachment or a handheld electric mixer, cream sugar and butter for several minutes until lighter in color and texture.
Add in vanilla extract and egg whites. Continue to mix until one cohesive mixture, about 5 minutes. This will most likely require that you stop and use a spatula to get the batter on the sides of the bowl.
Sift flour using a fine mesh colander (This is a critical step. I don't like adding another item to clean either, but it is key to the texture of the cookies). Gradually add in flour while mixer is running. Add salt.
Fit a piping bag with a 1/2'' tip. Spoon batter into piping bag- I like to place piping bag into a cup and then add the batter in.
Prepare a baking sheet with parchment paper or silpat. Pipe batter into circles (2'' diameter or 2'' long)- the technique will matter here so see video above for how to do this.
Bake until the outside part of the cookie is golden brown but the rest is still white, about 8 minutes.