01 -
Preheat the oven to 325°F. Line an 8x8-inch metal baking pan with parchment paper, leaving an overhang, and spray with nonstick cooking spray.
02 -
In a small saucepan set over medium-low heat, melt the butter. Swirl the pan occasionally and continue to cook, increasing the heat to medium. Swirl the pan until the butter develops a nutty aroma and brown bits start to form at the bottom. Once the bits turn amber, remove from heat and pour into a large mixing bowl, scraping the brown bits into the bowl.
03 -
Using a rubber spatula, add the powdered sugar to the hot browned butter and combine until a thick paste forms. Let cool until barely warm.
04 -
Vigorously whisk in the eggs, egg yolk, and vanilla for about 30 seconds, or until very smooth.
05 -
Whisk in the cocoa powder until evenly incorporated.
06 -
Using the spatula, fold in the all-purpose flour, malted milk powder, cornstarch, and salt until combined. Stir in the chocolate chips. The batter will be very thick.
07 -
Spread the brownie batter evenly into the prepared pan. Place in the oven and bake for 30 to 33 minutes, or until the brownies are set and a cake tester inserted into the center has moist crumbs attached. Do not overcook as they will set as they cool.
08 -
Let the brownies cool completely before cutting into squares. Sprinkle with flaky sea salt if desired.
09 -
Store brownies in an airtight container at room temperature for up to 3 days or in the fridge for up to 5 days. Serving chilled increases fudginess.