In a small bowl, whisk together the flour, cream of tartar, baking soda and kosher salt. Set aside.

In the bowl of an electric mixer, cream the butter and sugar together until light and fluffy. Add the eggs to the sugar mixture one at a time, incorporating after each addition. Add the half and half and vanilla, beat well. Slowly add the dry ingredients and mix thoroughly. Remove from the mixer and cover. Chill for 1-2 hours.

Whisk together the cinnamon and remaining sugar, set aside.

Preheat the oven to 350 degrees. Drop by rounded teaspoonfuls onto a baking sheet lined with parchment paper leaving about 2 inches in between each. (They spread like mad.) Sprinkle VERY generously with the sugar mixture. Bake for 12-13 minutes or until the edges are golden brown.

Cool the cookies on the sheet for 2 minutes and then transfer to a wire rack to cool completely.