Preheat your oven to 350°F (175°C).
In a large mixing bowl, cream together the softened butter and 1 cup of granulated sugar until light and fluffy, about 2-3 minutes.
Add the room temperature egg and vanilla extract to the butter mixture and mix until fully incorporated.
In another bowl, whisk together the flour, cream of tartar, baking soda, salt, and ground cinnamon. Gradually add this dry mixture to the wet ingredients, mixing on low speed until just combined.
Cover the dough and chill in the refrigerator for about 30 minutes.
Line your baking sheets with parchment paper. In a small bowl, combine 2 tablespoons of granulated sugar with 1 teaspoon of ground cinnamon.
Scoop the dough into rounded tablespoons and roll each ball in the cinnamon-sugar mixture until fully coated.
Place the dough balls on the prepared baking sheets, spacing them about 2 inches apart. Bake for 10-12 minutes.
Let the cookies cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.