2In a medium bowl sift together flour, cocoa powder, cream of tartar and baking soda.
In a large bowl cream butter and sugar until light and fluffy. Add eggs and beat to combine. Gradually add flour mixture and mix well.
3Form dough into balls and coat by tossing in a small bowl that has 1/4 c sugar, 2 tsp. of cinnamon and a 1/2 tsp of chili powder( optional). Place about 3 inches apart on parchment lined baking sheets. Bake until cookies are set in the center and begin to crack, about 8 minutes, rotating sheets halfway through. Let cookies cool about 5 minutes. Remove from sheets to wire rack and cool completely.