Lemon Sugar Cookies

1. Either on the stovetop or in the microwave (30 to 45 seconds), heat the butter until it’s half melted. Give it a good mix to break up those soft butter chunks – it will basically look like cottage cheese. Pour into a large bowl and whisk with the sugar until smooth. 
2. Add the egg yolk, vanilla, zest, and lemon juice and whisk until creamy.
3. Whisk in the salt, baking soda, and cream of tartar to distribute. Switch to a silicone spatula and fold in the flour until it disappears into the dough. Cover the bowl and chill for 20 minutes. (see notes for longer chilling instructions)
4. In the meantime, preheat the oven to 350F and line a large baking sheet with parchment paper.
5. In a small dish, use your fingers to toss together the lemon sugar ingredients. 
6. Using a large cookie scoop (3 tablespoons worth), scoop the dough into the lemon sugar and toss to coat. Place 5 to 6 cookies on the baking sheet spaced 4 fingers apart. 
7. Bake for 10 to 12 minutes (11 is the sweet spot for me) or until the cookies are domed and puffed with a slightly underdone center. 
8. Allow to cool on the pan for about a minute, then transfer to a cooling rack where they will settle and flatten. Bake the rest of the batch as directed. 
9. Once cooled, they’re ready to enjoy!