01 - Set oven temperature to 350°F and line two baking sheets with parchment paper.
02 - Whisk together flour, cream of tartar, baking soda, and salt in a medium bowl and set aside.
03 - Beat softened butter and 1 1/2 cups sugar in a large bowl until light and fluffy, about 2 to 3 minutes.
04 - Add eggs one at a time, beating thoroughly after each addition, then mix in vanilla extract.
05 - Gradually add dry mixture to wet ingredients, stirring until just combined to form dough.
06 - Mix granulated sugar and ground cinnamon in a small bowl for coating.
07 - Portion dough into tablespoon-sized balls and roll each thoroughly in the cinnamon sugar mixture.
08 - Place dough balls 2 inches apart on the prepared sheets to prevent spreading together.
09 - Bake for 9 to 11 minutes until edges are set but centers remain slightly soft.
10 - Let cookies cool on baking sheets for 5 minutes, then transfer to wire racks until completely cooled.