Mexican Hot Chocolate Cookies

Alright, here it is:

Mexican Hot Chocolate Cookies (courtesy of Martha Stewart)

2 1/4 c.               all-purpose flour
1/2 c.                  unsweetened cocoa powder
2 tsp.                  cream of tartar
1 tsp.                  baking soda
1/2 tsp.               coarse salt
1 c. (2 stix)         unsalted butter, room temperature
1 3/4 c.               sugar
2                         large eggs
1 1/2 tsp.            cinnamon  *recipe calls for 2 tsp. I found this to be just a smidge better
1/2 tsp.               chile powder

1. Preheat oven to 400 degrees, with racks in upper and lower thirds. In a medium bowl, sift together flour, cocoa powder, cream of tartar, baking soda, and salt. In a large bowl, using an electric mixer, beat butter and 1 1/2 cups sugar on medium speed until light and fluffy, about 2 minutes. Scrape down side of bowl. Add eggs and beat to combine. With mixer on low, gradually add flour mixture and beat until combined.
2. In a small bowl, combine remaining 1/4 cup sugar, cinnamon, and chile powder (if using). Using heaping tablespoons, form balls of dough and roll in cinnamon-sugar mixture. Place, about 3 inches apart, on two parchment-lined baking sheets. Bake until cookies are set in center and begin to crack, about 10 minutes, rotating sheets halfway through. Let cookies cool on sheets on wire racks 5 minutes, then transfer cookies to racks to cool completely. (Store in an airtight container, up to 1 week.)