Preheat Oven:

Preheat your oven to 400°F (200°C).

Line baking sheets with parchment paper.

Mix Dry Ingredients:

In a medium bowl, whisk together the all-purpose flour, cream of tartar, baking soda, and salt. Set aside.

Cream Butter and Sugar:

In a large bowl, using an electric mixer, beat the softened butter and 1½ cups granulated sugar until light and fluffy.

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

Stir in the vanilla extract.

Combine Wet and Dry Ingredients:

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

Prepare Rolling Sugars:

In a small bowl, combine 2 tablespoons granulated sugar with 2 teaspoons ground cinnamon.

Divide this mixture evenly into two separate bowls.

Add the red sanding sugar to one bowl and the green sanding sugar to the other, mixing each until well combined.

Shape and Coat Dough Balls:

Scoop tablespoon-sized portions of dough and roll them into balls.

Roll half of the dough balls in the red cinnamon-sugar mixture and the other half in the green cinnamon-sugar mixture, ensuring they are evenly coated.

Bake:

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

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

Remove from the oven and allow the cookies to cool on the baking sheets for 2 minutes before transferring them to wire racks to cool completely.