In a medium bowl, stir together all ingredients until thoroughly combined. Set aside.
Prepare Cookies
In a bowl, combine all-purpose flour, cream of tartar, baking soda, cardamom, and salt. Set aside.
In a large bowl, cream together brown sugar and butter at medium high speed until light and fluffy, about 3 minutes. Add eggs and vanilla and beat until thoroughly combined, about one minute.
Gently add flour mixture to the creamed butter, and mix on low speed until a cohesive dough is formed. Transfer the prepared cookie dough to a covered container and refrigerate for one hour.
Preheat oven to 375°F and set aside two parchment lined baking sheets.
Remove cookie dough from the refrigerator and shape it into 2-inch balls (about 1½-2 tablespoons worth of dough). Roll the balls around in the prepared chai spice mixture and place them 2-inches apart on prepared baking sheets.
Bake until the edges are lightly browned, about 10 to 12 minutes. Remove from oven and cool for 5 minutes, then transfer to a wire rack to cool completely.