Directions

1. In large mixing bowl with an electric mixer combine the butter, 1/2 cup sugar, brown sugar, and beat on medium-high speed until creamed and well combined, about 3 minutes.
   
2. Then add the egg, vanilla, and beat on medium-high speed until well combined, light and fluffy, about 3 minutes.
   
3. In a medium bowl combine the flour, baking soda, cream of tartar, and salt. Add dry ingredients to wet ingredients, and beat on low speed until just combined, about 1 minute.
   
4. Refrigerate dough for at least 2 hours or overnight.
   
5. Preheat oven to 350 degrees. Line a baking sheet with parchment paper or spray with cooking spray.
   
6. In a small bowl, combine 1/4 cup sugar and cinnamon and stir to combine.
   
7. Using a tablespoon to measure dough, form dough balls with your hands. Dredge each dough ball through cinnamon and sugar mixture and place on cookie sheet.
   
8. Bake for about 10 minutes, or until edges have set and tops are just set. For firmer cookies, bake a minute or two longer. Cookies firm up as they cool.
   
9. Allow cookies to cool on baking sheet for about 10 minutes before serving. Cookies will keep airtight at room temperature for up to 1 week or in the freezer for up to 6 months. Unbaked cookie dough can be stored in an airtight container in the refrigerator for up to 5 days, or in the freezer for up to 4 months.