Preheat your oven to 350°F (175°C). Line a 9x9-inch baking pan with parchment paper, leaving an overhang for easy removal. This ensures a clean lift-out later!
In a spacious mixing bowl, gently combine the melted butter and brown sugar. Stir until the mixture is beautifully smooth and evenly blended.
Whisk in the eggs, one at a time, ensuring each is fully incorporated before adding the next. Then, stir in the vanilla and invigorating peppermint extracts for that signature holiday flavor.
In a separate medium bowl, lightly whisk together the all-purpose flour, cornstarch, baking powder, and kosher salt. This helps distribute the leavening evenly.
Gradually add the dry ingredient blend to the wet mixture, stirring just until no dry streaks remain. Be careful not to overmix! Gently fold in the white chocolate chips, creating delightful pockets of sweetness throughout.
Transfer the luscious batter to your prepared baking pan. Spread it into an even layer using a spatula to ensure consistent baking.
Bake for 30 to 35 minutes, or until the top is a beautiful golden brown and a toothpick inserted into the center comes out with just a few moist crumbs (no wet batter!).
Let the blondies cool in the pan for about 10 minutes. This is the perfect time to get your festive toppings ready!
In separate microwave-safe bowls, melt the milk chocolate chips and white chocolate chips. Heat in short bursts (20-30 seconds), stirring well between each interval until smooth and glossy.
Artfully drizzle both melted chocolates over the still-warm blondies. Immediately sprinkle the crushed peppermint candies over the top – this helps them stick perfectly for that holiday crunch!
Allow the blondies to cool completely at room temperature before slicing into charming squares. This ensures the chocolate toppings set beautifully and makes for clean cuts. Enjoy your homemade festive treat!