Set your oven to 325 degrees.
In a small/medium bowl combine your cinnamon and sugar for rolling the dough in later. Set aside.
Line your baking sheet(s) with parchment paper or a silicon mat.
In a large bowl mix your butter and sugar until fluffy.
Add in your egg, egg yolk, and vanilla. Mix until combined.
Mix in your salt, baking soda, cream of tartar, and cinnamon. Mix until combined.
Slowly mix in your flour until just combined.
Scoop out 1-2 Tbsp. of dough and roll into a ball. Then roll that ball into your cinnamon/sugar mixture you set aside earlier. Do this for each ball and place on your baking sheet 2 inches apart.
Bake for 10 minutes, rotating the pan halfway through.
Let cool for 5-10 minutes.
