Start by preheating the oven to 375 degrees F and large a baking sheet with parchment paper.s
First, start by mixing the dry ingredients together in a medium bowl. Starting with the flour, cream of tartar, baking soda, and salt.
Start by creaming the butter and sugar together using the paddle attachment of your stand mixer or hand mixer. This will take about 3-4 minutes.
Add in the egg yolk, vanilla and 1 tablespoon of water and mix until everything is mixed together. Scrape the sides if needed.
Add the dry mixture to the wet mixture and mix until just incorporated.
Using a small cookie dough scooper, scoop out 12 cookie dough balls, roll them in between the palm of your hands, then roll them in the cinnamon-sugar mixture. Place the cookies on the baking sheet making sure to leave 3 inches between each one.
Bake for 10 minutes. The cookies will be puffy and pretty soft still, don't worry about that, they will continue baking as they cool down. Let the cookies sit on the baking sheet for 10-15 minutes then transfer to a wire rack to cool completely.