Preheat the oven to 350 degrees. Line a few baking sheets with parchment and set aside.
For the chai spice mix - mix all the ingredients in a small bowl. Store any remaining spice in an airtight container.
For the cookies - In the bowl of a stand mixer, combine the softened butter, sugar and brown sugar. Cream until smooth.
Add in the eggs and vanilla. Mix again until smooth - scraping down the sides and mixing again when needed.
Add in the remaining dry ingredients: flour, baking soda, salt, cream of tartar and the chai spice. Mix well, scraping the sides and mixing thoroughly. The dough will be sticky.
For the coating - in a small bowl, combine the sugar and chai spice. Whisk to combine.
Using a heaping tablespoon or a small ice cream scoop, scoop out enough dough to form a golf ball sized ball.
Roll in the sugar coating and place on the parchment lined baking sheets. Allow about three inches of spread around each cookie.
Bake in the preheated oven for 10 minutes. The edges should just be set and slightly browned and the center no longer shiny. Allow to cool.
Notes
Tips:
These cookies will spread outward - ensure enough space by placing the dough about three inches apart on the baking sheet.
Do not overbake - the cookies should have a crunchy edge with a soft, chewy center. The cookies are done baking when the edges are set and just slightly browned and the center is no longer glossy.
StorageThey can be kept for up to 7 days on the counter or in the fridge in an air tight container. Or, they can be frozen up to a year.