Preheat oven to 350 degrees F.
Grease 9x13" baking pan with butter or cooking spray.
Combine hot coffee and butter in medium bowl, stirring until butter is melted. If the butter doesn't melt all the way, microwave for 30 seconds.
In a large bowl, combine eggs, milk, vanilla, and sugar, stirring until well combined.
In a medium bowl combine flour, cocoa powder, cinnamon, cayenne pepper, baking powder, baking soda, and salt, stirring until well combined.
Add flour mixture to egg mixture, stirring until about halfway combined, then add coffee mixture, stirring until well combined.
Stir in chopped chocolate.
Pour batter into the pan.
Bake in preheated oven for 45-50 minutes, until a toothpick comes out with some loose crumbs on it.
Let the cake cool completely.
Once cake is cooled, combine condensed milk, evaporated milk, and chocolate milk and stir well to combine.
Poke lots of holes in the cake with a toothpick or a fork - the more the better, so it soaks up all the milks!
Pour the milk mixture over the cake.
Refrigerate at least an hour.
Make whipped topping by combining heavy cream, cocoa powder, cinnamon, and whipping until stiff peaks form. I use my electric mixer for this but if you want a good arm workout - use a whisk and your arm!
Spread whipped topping over chilled cake.
Dust with powdered sugar, cinnamon, and a sprinkle of more cayenne, if desired!
Slice and enjoy!