Step 1

Preheat oven to 350 degrees F (175 degrees C). Line a 12x15-inch baking pan with parchment paper, leaving about 3 inches of paper overhanging 2 sides to use as handles.

Step 2

Place the butter in a microwave-safe bowl, and cook on Medium until the butter is about half melted, about 1 minute. Mash the butter with sugar until well combined, and stir in eggs one at a time, incorporating each one before adding the next. Mix in vanilla extract.

Step 3

Sift the cocoa, flour, cinnamon, pequin pepper, salt, and baking powder into a bowl. Sprinkle in any salt caught in the sifter. Mix the flour mixture into the butter mixture, stirring to blend well, and pour the batter into the prepared baking pan.

Step 4

Bake in the preheated oven until a toothpick inserted into the center comes out with moist crumbs, 20 to 25 minutes. Let cool in the pan, and use parchment paper handles to remove the brownies for slicing.