1. Combine butter and sugars in a large bowl and beat with an electric mixer on medium until very light and fluffy, 8 to 10 minutes, scraping down sides of bowl occasionally. Add egg and vanilla and beat well to combine.
2. In a second large bowl, whisk together flour, baking soda, cream of tartar, and salt, then stir in chocolate chips. Add flour mixture to bowl with butter mixture and beat on low until dough begins to come together. Gradually increase speed to high and beat until dough is smooth. Cover bowl and refrigerate at least 1 hour and up to 1 day.
3. Center a rack in the oven and heat to 350 degrees. Using a tablespoon measure, scoop and shape dough into 1" balls, roll in extra granulated sugar, and place on a parchment-lined baking sheet spaced about 2" apart. Bake until edges are golden, 10 to 12 minutes. Transfer cookies to a wire rack and let cool. Repeat with remaining dough.
Source: Hannaford fresh Magazine, November - December 2017