In a separate bowl, whisk together flour, cornstarch, cream of tartar, baking soda, and salt.
3 cups all-purpose plain flour, 2 teaspoons cornstarch, 1 ½ teaspoons cream of tartar, ¾ teaspoon baking soda, ½ teaspoon salt
Gradually (with mixer on low-speed), add flour mixture to butter mixture until completely combined. Be sure to scrape the sides and bottom of the bowl to ensure all ingredients are completely incorporated.
Scoop cookie dough by level 1 ½ Tablespoon-sized scoop and roll between your palms until you have a smooth ball. Roll ball through powdered sugar and place on baking sheet. Repeat with remaining dough, spacing cookies at least 2” apart.
Powdered sugar for rolling cookies
Bake on 350F for 9-11 minutes and allow to cool completely on baking sheet. Enjoy!
Video
Notes
¹I typically need two full lemons for this. When zesting your lemons, make sure to not zest too deeply, avoid the white papery “pith” which is bitter and will make your cookies bitter.