Preheat oven to 375° F. Line two cookie sheets with parchment paper and set aside.
In a standing mixer, add the cold cubed butter, granulated sugar, and brown sugar. Make sure NOT to use room temperature butter, or your cookies won't hold their shape. Turn on medium speed, and gradually increase to high speed. Mix on high for about 2-3 minutes, until there aren't any more cubes of butter and the mixture is creamy.
1 cup unsalted butter , 1 cup granulated sugar, ½ cup light brown sugar, packed
In a separate bowl, whisk together the dry ingredients (flour, cream of tartar, baking soda, sea salt, cinnamon, and cornstarch) and set aside.
2 ¾ cup all-purpose flour, 1 ½ teaspoon cream of tartar, ½ teaspoon baking soda, 1 teaspoon fine sea salt, 1 ½ teaspoon ground cinnamon, 1 teaspoon cornstarch
Once the butter and sugars are done mixing, add the eggs and the vanilla extract and mix on medium speed until completely combined. Make sure to scrape down the sides of the bowl so that it's well mixed.
2 large eggs, 1 tablespoon vanilla extract
Add the dry ingredients to the standing mixer and stir in on lowest speed. Don't overmix! Once all of the dry ingredients are mixed in, it's done.
In a small bowl, stir together ¼ cup of granulated sugar with a tablespoon of ground cinnamon. Roll the cookie dough into 18 balls and then roll each ball in the cinnamon-sugar mix until well coated. Don't over-handle the doughu002du002dyour warm hands will melt the butter. Evenly spread out the balls of cookie dough on the lined cookie sheets and bake one cookie sheet at a time (or in two separate ovens) for about 9-10 minutes. They will be really soft, but leaving them to cool on the pan will allow them to solidify more.
½ cup granulated sugar, divided**, 2 tablespoon cinnamon, divided**
Allow the cookies to cool on the cookie sheet for at least 10 minutes. Mix ¼ cup of granulated sugar with a tablespoon of ground cinnamon. Once the cookies have solidified enough to pick them up, gently re-coat them in the cinnamon-sugar mix. This step is optional, but I highly recommend!
½ cup granulated sugar, divided**, 2 tablespoon cinnamon, divided**
Enjoy!