Preheat oven to 350°F (175°C).
Line baking sheets with parchment paper or silicone mats.
In a large bowl, beat softened butter and 1 ½ cups sugar until light and fluffy (about 2-3 minutes).
Mix in eggs one at a time, then add vanilla extract.
In a separate bowl, whisk together flour, cream of tartar, baking soda, and salt.
Gradually add dry ingredients to the butter mixture, mixing just until combined.
In a small bowl, mix ¼ cup sugar and cinnamon.
Roll dough into 1-inch balls, then coat each in the cinnamon-sugar mixture.
Place dough balls 2 inches apart on baking sheets.
Bake for 9-11 minutes until edges are lightly golden (centers will look slightly underbaked).
Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack.
