Instructions

1. Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
2. In a large mixing bowl, cream together the softened butter and 1 ¼  cups of granulated sugar and ¼ cup brown sugar until light and fluffy. 
3. Add the vanilla extract. Next, add the egg and the egg yolk, one at a time, beating well after each addition. Make sure to scrape down the sides of the bowl to ensure everything is well incorporated.
4. In a separate bowl, whisk together the flour, cream of tartar, baking soda, salt and cinnamon. 
5. Gradually add the dry ingredients to the butter mixture, mixing until just combined. Be careful not to overmix, as this can result in tough cookies.
6. In a small bowl, combine the remaining 2 tablespoons of granulated sugar and the ground cinnamon for rolling. Set aside. 
7. Shape the dough into 1 1/2- inch balls and roll each ball in the cinnamon-sugar mixture until fully coated. Next pop dough balls in the freezer for 15 minutes. After chilling, place the coated dough balls onto the prepared baking sheet, spacing them about 2 inches apart. Note: Sprinkle the extra remaining cinnamon/sugar mixture over the cookies immediately after they come out of the oven. 
8. Bake the cookies for 8 to 10 minutes or until they are lightly golden around the edges. The centers should still be slightly soft. Now you want to sprinkle the extra or remaining cinnamon/sugar mixture over the hot cookies.
9. Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
10. Once cooled, indulge in the heavenly aroma and enjoy these delightful snickerdoodle cookies with a glass of milk or a hot cup of coffee!
11. Store Snickerdoodle Cookies in an airtight container at room temperature. They will stay fresh for 3 to 4 days. I love to pop them in the microwave for 8 to 10 seconds. Aww, they taste like they came straight from the oven.

Do ahead/Freeze tip: uncooked cookie dough can be frozen for up to three months. Also cooked cookies freeze well for up to three months as well.