Preheat Oven: Heat oven to 350°F (175°C). Line an 8x8 or 9x9 baking pan with parchment paper and lightly grease.
Mix Butter & Sugars: In a microwave-safe bowl, melt the butter. Stir in granulated sugar and brown sugar until glossy and well combined. Cool slightly.
Add Eggs & Vanilla: Whisk in the eggs one at a time until smooth. Mix in vanilla extract.
Combine Dry Ingredients: In a separate bowl, sift together flour, cocoa powder, and salt. Fold the dry mixture into the wet mixture until just combined.
Add Chocolate Chips: Fold in chocolate chips if using.
Bake: Pour batter into the prepared baking pan. Bake for 28–35 minutes, or until edges are firm and center is set but soft.
Add Candy Cane Topping: Remove brownies from the oven and immediately sprinkle crushed candy canes over the hot brownies.
Optional Drizzle: Melt white chocolate and semi-sweet chocolate separately; drizzle over brownies.
Cool & Slice: Let brownies cool completely before cutting into squares.