In a large bowl, whisk together the flour, chile powder, cinnamon, and salt
In the bowl of a stand mixer fitted with the paddle attachment, combine the butter, confectioners' sugar, egg yolk, and vanilla extract. Beat on medium speed, scraping down the sides and bottom of the bowl halfway through, until smooth, 2-3 minutes. (Alternately, use a large bowl and a hand mixer)
Turn the mixer off and add the flour mixture. Mix on low speed just until a crumbly dough forms, about 1 minute. Stir in the chopped chocolate with a rubber spatula.
Transfer the dough to a large sheet of plastic wrap. Form into a 1 1/2-inch diameter log, then shape that into an oval, luchador-mask shape. Gently wrap in the plastic, twisting the ends tightly to help form a cylinder shape. Chill in the fridge for 2 hours, rotating it a few times to help it keep its shape.
Place the turbinado sugar in a large shallow bowl or plate. Crack the egg into a small bowl and stir with a fork until no streaks of yolk remain.
Position a rack in the middle of the oven and preheat to 350°F. Line a baking sheet with parchment paper or a nonstick baking mat
Unwrap the chilled dough and use a pastry brush to lightly coat the outside with the beaten egg. Roll the log in the turbinado sugar, firmly pressing the sugar into the sides of the log to help it stick. Use a sharp, thin knife to slice the log into approximately 16 1/2-inch thick slices. Arrang the slices on the baking sheet, spacing about 2 inches apart.
Bake until the tops of the cookies look matte and are very fragrant, 16-18 minutes. Let cool completely on the baking sheet. These will feel very soft when hot, but will firm up as they cool.