1. Preheat the oven to 375°F and line baking sheets with parchment paper.

2. In a large bowl, beat the softened butter and 1 1/2 cups sugar until light and fluffy.

3. Add the eggs one at a time, then mix in the vanilla extract until smooth.

4. In a separate bowl, whisk together the flour, cream of tartar, baking soda, and salt.

5. Gradually add the dry ingredients to the wet ingredients and mix just until a soft dough forms.

6. In a small bowl, stir together 1/4 cup sugar and the cinnamon for the coating.

7. Scoop the dough into 1 1/2 tablespoon portions and roll each into a ball.

8. Roll each dough ball in the cinnamon sugar mixture until fully coated.

9. Place the dough balls on the prepared baking sheets about 2 inches apart.

10. Bake for 8 to 10 minutes, until the edges are set and the centers still look slightly soft.

11. Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.