Preheat your oven to 375°F (190°C). Line two baking sheets with parchment paper or silicone baking mats.

In a large mixing bowl, cream together the softened butter and 1 1/2 cups sugar until smooth and light, about 2-3 minutes.

Add the eggs one at a time, beating well after each addition.

In another bowl, whisk together the flour, cream of tartar, baking soda, and salt.

Gradually add the dry ingredients to the butter mixture, mixing until just combined.

In a small bowl, combine the 1/4 cup sugar and cinnamon.

Scoop about 1 tablespoon of dough and roll it into a ball.

Roll the dough balls in the cinnamon-sugar mixture until well coated.

Place the coated balls on the prepared baking sheets, spacing them about 2 inches apart.

Bake in the preheated oven for 8-10 minutes, or until the edges start to turn golden and the centers are set but still soft.

The cookies will puff up initially and then flatten out as they bake.

Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.