Start with the dry ingredients. Add the all purpose flour, cream of tartar, baking soda, and salt to a bowl. Whisk all of the ingredients together until they are well combined. Set aside.
Add the butter, brown sugar, and ½ cup granulated sugar to a standing mixer. Beat on medium speed for 3-5 minutes until the mixture turns light in color and is creamed and fluffy. Be sure to scrape the sides throughout the beat time.
Meanwhile, add the eggs and vanilla to a separate bowl and gently whisk the eggs together so the egg yolk, egg white, and vanilla are combined.
Slowly add the egg mixture to the creamed butter and sugar and beat until the egg combines with the sugar and butter and becomes light and fluffy.
Add the dry ingredients to the wet ingredients and mix until just combined. Be sure there are no flour clumps at the bottom of the mixing bowl.
Transfer the cookie dough to an airtight container and refrigerate the dough for at least 2 hours or overnight for best results.
Remove the cookie dough from the refrigerator and let it sit at room temperature for 10 minutes.
Preheat the oven to 350ºF and line a baking sheet with parchment paper.
While the dough is sitting, add the cinnamon and 2 tablespoons of granulated sugar to a bowl and mix.
Use a tablespoon scoop to scoop a heaping tablespoon of cookie dough into your hands and roll the dough into a ball.
Roll the dough into the cinnamon and sugar until the ball is completely covered. Place the dough on the lined baking sheet and repeat until all the dough has been rolled in cinnamon sugar.
Be sure to space the cookie dough balls far enough apart, these cookies do spread a little bit.
Bake at 350ºF for 10-12 minutes. The snickerdoodles should begin to crack on the tops when they are almost done.
Remove the cookies from the oven and transfer them to a cooling rack.