In a large bowl, cream together the butter, 1 cup sugar and the brown sugar with an electric mixer. Add the eggs and vanilla and beat until smooth.
Add in the flour, salt, baking powder, baking soda and cream of tarter. Stir just until smooth. Cover the dough and refrigerate for 30 minutes.
Preheat the oven to 350°F. Line a baking sheet with parchment paper or a silicone mat.
In a small bowl, stir together the remaining 1/4 cup sugar and cinnamon. Roll the dough into 1 1/2 inch size balls and then roll into the cinnamon sugar. Place onto the prepared baking sheet about 2 inches apart.
Bake for 9-11 minutes, or until the edges are slightly golden brown. The centers will look slightly under cooked and that’s okay. Let cool on baking sheet for 5 minutes and they will firm up. Then transfer to a wire rack to cool.