In a large bowl, cream together the butter and sugars with a mixer on high speed. Add the egg and vanilla and beat until combined.
In another bowl, combine the flour, salt, baking soda, and cream of tartar.
Pour the dry ingredients into the wet ingredients and mix well. Chill dough in the fridge for about an hour.
After dough has chilled, preheat oven to 300 degrees.
In a small bowl, combine the sugar with the cinnamon for the topping.
Take around 2 tablespoons of the dough and roll it into a ball for each cookie. Roll it in the cinnamon/sugar mixture and place onto a parchment lined cookie sheet. Slightly flatten each ball with the palm of your hand.
Bake the cookies for 12 to 14 minutes and no more. The cookies may not seem done but will continue to cook after removed from the oven and left to sit for a while.