Whisk cocoa powder with hot melted butter before adding other ingredients to intensify the chocolate flavor and eliminate any bitter, raw cocoa taste.

Lightly toast the cinnamon in a dry pan for 30 seconds before adding to enhance its warm, complex notes and prevent the flavor from becoming overpowering.

Mix only until ingredients are just combined to avoid developing gluten, which leads to tough, cake-like brownies instead of the desired fudgy texture.

Reserve some chocolate chips to press into the batter surface before cooking so they melt slightly and create pockets of gooey chocolate throughout the brownie.

Preheat your cast-iron skillet in the oven at 350°F for 5 minutes, then add batter for even heat distribution and a golden, crispy edge while keeping the center fudgy.