Recipe

1. Preheat your oven to 375F. Line two large cookie sheets with parchment paper or silicone baking mats (always recommended for cookies). Set aside.
2. Make the topping: Combine the granulated sugar and cinnamon together in a small bowl.
3. Make the cookies: whisk together the flour, cream of tartar, baking soda, cinnamon, and salt together in a medium sized bowl.
4. In a larger bowl using a hand mixer or stand mixer fitted with a paddle attachment, beat the butter and granulated sugar together on high speed until combined smooth and creamy, about 2 minutes. Add the egg, egg yolk, and vanilla extract. Beat on medium-high speed until combined. Scrape down the sides and up the bowl with a rubber spatula as needed. With the mixer running on low speed, slowly add the dry ingredients to the wet ingredients in 3 different parts, the dough will be thick.
5. Roll cookie dough into balls about 1.5 Tablespoons of cookie dough each. Roll the dough balls in cinnamon-sugar topping. Sprinkle extra cinnamon-sugar if desired. Arrange 3 inches apart on the cookie sheets.
6. Bake your cookies for 10 minutes. The cookies will be very soft and puffy. When they are still very warm, lightly press down on them with a spoon or fork to help flatten them out. Allow cookies to cool on the baking sheets for 10 minutes and transfer to a wire rack to cool completely.
Note: cookies remain soft and fresh for 7 days in an airtight container at room temperature!