In a medium mixing bowl, use a hand held mixer to cream together the butter and 1/3 cup of sugar until light and fluffy. Add the egg yolk and vanilla extract and continue to beat on medium speed until the mixture is combined and smooth.
Sift the flour, cream of tartar, baking soda, and salt over the wet ingredients. Stir just until no dry streaks remain. Note – I recommend sifting the dry ingredients over the wet ingredients to make sure there are no lumps.
Cover the bowl with plastic wrap and refrigerate the dough for at least 30 minutes.
Preheat the oven to 375F degrees and adjust the oven rack to the middle position. Line a baking sheet with a piece of parchment paper.
In a shallow baking dish, mix together the 2 tablespoons of sugar and cinnamon.
Using a medium cookie scoop (I use a #40), scoop even portions of the chilled cookie dough and gently roll the cookie dough into a ball with your hands. Then, roll each cookie dough ball liberally through the cinnamon sugar. Place the cookies at least 2 inches apart on the prepared baking sheet. Note – the number of cookies you get will depend on the size of the cookie scoop you use.
Bake for 10-12 minutes, or until the edges of the cookies are golden. Cool the cookies on the baking sheet set on a wire rack for 10 minutes, then transfer the cookies to the wire rack to cool completely. Enjoy!