Preheat oven to 350°. Line cookie sheet with parchment.
In a small bowl whisk together flour, baking soda, salt, and cream of tarter.
1½ cups flour, ½ teaspoon baking soda, ¼ teaspoon salt, 1 teaspoon cream of tartar
In a stand mixer or with hand beaters, beat butter and sugar until light and fluffy, approximately 2 minutes.
½ cup butter, ¾ cup sugar
Add in egg and beat for another minute.
1 egg
Add dry ingredients to the bowl. Mix until just combined. Gather the dough into a ball and transfer to lightly floured counter or board.
Gently pat dough into a rectangle, and then finish rolling it out until it is ¼ inch tall. Using a round cookie cutter, cut out as many circles as you can. Transfer cut-outs to the cookie sheet. Gently gather up the scraps and repeat until all the dough is used.
Bake for 9-10 minutes or until slightly puffy and the edges are very lightly golden. If you are cooking multiple sheets at once, be sure to rotate halfway through. Allow to cool on a cookie sheet until completely cool.