Mexican Hot-Chocolate Cookies

These rich chocolate cookies were a hit at my house. The addition of the cinnamon-sugar coating put them right over the edge.
We enjoyed them on the first day of spring with a glass of cold milk. But I will definitely bake up a batch on a cold snowy day next winter, and dip them into a mug of steaming hot cocoa.

Mexican Hot-Chocolate Cookies
adapted from Martha Stewart Everyday Food

2 1/4 cups flour
1/2 cup unsweetened cocoa powder
2 tsp cream of tartar
1 tsp baking soda
1/2 tsp coarse salt
1 cup (2 sticks) unsalted butter, room temperature
1 3/4 cups sugar, divided
2 eggs
1 cup chocolate chips (not in the original recipe, but I thought they were a worthy addition)
2 tsp cinnamon

Preheat oven to 400 degrees F. 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 of the sugar until light and fluffy, about 2 minutes. Scrape down sides of bowl. Add eggs and beat to combine. With mixer on low, gradually add flour mixture and beat until combined. Add chocolate chips (you will probably have to stir with a wooden spoon at this point).
In a small bowl, combine the remaining 1/4 cup sugar with the 2 tsp cinnamon. Using heaping tablespoons, form balls of dough and roll in cinnamon-sugar mixture. Place about 3 inches apart on parchment-lined baking sheets. Bake until cookies are just set (7-8 minutes), rotating sheets halfway through (the recipe is written to cook for 10 minutes, until the centers begin to crack...around here, we don't like our cookies crispy, soft and chewy for us please. If you prefer a crisp cookie, cook the full ten minutes.). Let cookies cool on sheets on wire racks 5 minutes then transfer cookies to racks to cool completely.