Fire up the oven to 350°F (175°C).
Set a baking sheet with parchment paper or a silicone mat.
Grab a bowl and whip the butter, white, and brown sugar until they’re fluffy like clouds.
Beat in the egg and vanilla, and mix till they’re tight.
In another bowl, whisk up the flour, cream of tartar, and baking soda.
Slowly fold the dry mix into the wet bowl. Stir until you can’t see the flour anymore.
Roll dough into little balls (about 1 inch wide).
Coat each with cinnamon sugar goodness until they’re excellent and covered.
Lay the sugary dough balls on your prepped sheet with a bit of space between them.
Bake them for 8-10 minutes until the edges say “hi” and the centres are still soft.
Leave cookies to chill on the sheet for 2-3 minutes, then move them to a wire rack to cool fully.