Preheat the oven to 400-degrees. Beat the butter on medium speed until it’s very light and creamy, about 3 minutes, scraping down the sides and bottom of the bowl occasionally.
Slowly add the sugar, beating in on medium speed, until the sugar and butter are light and fluffy, about 2 to 3 minutes, scraping down once or twice.
Using medium-low speed, add the eggs one at a time, beating well after each addition.
Add the vanilla extract and beat on medium speed for about 1 minute.
In a medium bowl, whisk together the flour, kosher salt, baking powder, and baking soda.
Stir about ⅓ of the flour mixture at a time into the dough using low speed, alternating with the sour cream, beginning and ending with the flour. Scrape down the sides and bottom once or twice to make certain the ingredients are well combined. The dough will be soft.
Using a 1” ice cream lever scoop or a teaspoon, drop the dough onto a baking sheet lined with a Silpat liner or parchment paper.
Sprinkle the tops with additional sugar or sanding sugar and bake in a 400-degree oven for 10 minutes or until the tops are puffed and set and the bottom of the cookies are golden.
Let the cookies cool on the pans for a few minutes then transfer to a wire rack to cool completely.