Preheat the oven to 375 degrees F (190 degrees C).

Combine butter, brown sugar, and white sugar in the bowl of a stand mixer fitted with the paddle attachment; beat until smooth and creamy. Add eggs, 1 at a time, mixing well after each addition. Mix in cinnamon, chili powder, vanilla extract, and cayenne pepper.

Mix together flour, cocoa powder, salt, and baking soda in a medium bowl. Add flour mixture to butter mixture, a little at a time, mixing well after each addition. Gently fold in oats and chocolate chips. Cover batter and refrigerate for at least 30 minutes.

Roll dough into 12 golf ball-sized balls and place on a cookie sheet about 2 inches apart. Press down on each cookie to flatten to about 1/2 of its original height.

Bake in the preheated oven until edges are golden, 8 to 12 minutes. Cool on the baking sheet for 1 minute before removing to a wire rack to cool completely.