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

Melt white chocolate chips over a double boiler or in 20-second microwave intervals, stirring between each, to prevent seizing and ensure smooth, glossy distribution throughout the batter.

Reserve chopped peppermint bark pieces and fold them in at the very end with a spatula to maintain their texture and prevent them from breaking apart or melting into the batter.

Let eggs sit out for 15 minutes before beating to ensure they incorporate fully with the sugar, creating a lighter, airier batter for fudgier brownies with better texture.

Remove brownies when a toothpick inserted in the center still has a few moist crumbs clinging to it—they'll continue cooking as they cool, resulting in a perfectly fudgy center rather than dry, cake-like brownies.