To begin, preheat your oven to 350 and spray two pans with non-stick spray (or line with parchment paper).
To a large mixing bowl, add your butter and white sugar and beat them together with a mixer till creamy. Add your vanilla and egg and blend till incorporated.
To the same bowl, add your flour, cornstarch (or cream of tartar), baking soda, salt, cinnamon, ginger, cardamom and allspice. Stir together till you have a thick, smooth cookie dough.
Scoop out your cookie dough balls, and set them aside on a plate.
To a small bowl, add your white sugar, cinnamon, ginger, cardamom and allspice and stir together till the spices are evenly distributed among the sugar.
Take a cookie dough ball and roll it till it's entirely covered in the chai sugar topping. Place on your pan. Repeat till all cookie dough balls have been rolled sugar, and are spread evenly apart on your pans.
Bake in the oven for 9-11 minutes, or till the edges are set but the center looks a touch underdone. Let them cool on the pans at least 10 minutes before removing.
Stored in an airtight container these cookies taste best within 4 days.