To commence, preheat the oven to a temperature of 350 degrees Fahrenheit (175 degrees Celsius). Next, take an 8x8-inch square pan and carefully line it with parchment paper, allowing for some excess paper to drape over all edges.
In a small bowl, combine the espresso powder and coffee, stirring until the espresso powder is fully dissolved.
Combine flour, cocoa powder, cream of tartar, baking soda, salt, and a quarter teaspoon of cinnamon in a mixing bowl. Leave it aside for later use.
The electric mixer whirs as the butter, 1/2 cup of white sugar, and brown sugar are blended together in a bowl until they become light and fluffy. With the mixer still running, the espresso mixture, egg, and vanilla are added, and the ingredients are combined thoroughly. The flour mixture is gently folded in until a dough forms, being careful not to overmix. Using hands lightly dusted with flour, the dough is firmly and evenly pressed into the prepared pan.
In a small bowl, combine 1 tablespoon of white sugar and the remaining 1/2 teaspoon of cinnamon. Sprinkle the sugar mixture evenly over the dough.
The dough in the center of the pan should be baked until it feels slightly firm, which usually takes about 20 to 23 minutes in the preheated oven.
As the cookies come out of the oven, it is important to let them cool in the pan for approximately 10 minutes. Once slightly cooled, use the parchment paper edges to carefully transfer the cookies onto a wire rack. Allow them to cool completely before proceeding to cut them into bars.