In a large bowl, beat together the sugars and butter until light and fluffy. Beat in eggs and vanilla.
1 cup granulated sugar, ½ cup lightly packed brown sugar, 8 tablespoons butter, 2 eggs, 1 teaspoon pure vanilla extract
In a medium bowl, whisk together flour, cocoa powder, cinnamon, chile powders, baking soda, cream of tartar, and salt. Slowly add to the sugar mixture and mix until well combined. Chill dough in fridge for about 30 minutes, and preheat oven to 350°F.
1 ½ cups all-purpose flour, 1/2 cup cocoa powder, 2 teaspoons ground cinnamon, ½ teaspoon ground chile powder, 1/8 teaspoon ground cayenne pepper, 1 teaspoon baking soda, 1 teaspoon cream of tartar, ¼ teaspoon fine sea salt
When ready to bake, mix together granulated sugar and cinnamon together in a small bowl. Scoop dough into balls and roll in cinnamon-sugar mixture, then place on parchment-paper covered baking sheet, leaving plenty of space between cookies to allow for spreading. Chill any remaining cookie dough while you bake.
¼ cup granulated sugar, 2 teaspoons ground cinnamon
Bake for 10-12 minutes and transfer immediately to wire cooling rack.
Notes
Store in a cookie jar or airtight container for about 1 week.