Cream together the butter and sugar, then mix in the egg and vanilla.
In a separate bowl, whisk together the flour, baking soda, cream of tartar, cornstarch, salt, and cinnamon. Gradually mix into the butter mixture until just combined. The dough should be thick and pillowy soft.
Scoop out the dough using a cookie scoop (equivalent to 2 tablespoons). Roll the dough into balls with your hands and roll into the cinnamon-sugar mixture to coat.
Evenly space the dough on a lined baking sheet and bake for about 10 minutes. The edges should be just starting to brown.
Allow to cool on the baking sheet until set and enjoy!