01 -
Preheat oven to 175°C. Line an 20x20 cm square baking pan with parchment paper, allowing overhang for easy removal.
02 -
In a microwave-safe bowl, combine melted butter, oil, and chopped dark chocolate. Heat in 30-second intervals, stirring until smooth and glossy.
03 -
Whisk cocoa and espresso powders into the melted chocolate mixture to bloom and intensify flavor. Allow to cool slightly.
04 -
Using a mixer, beat granulated sugar, powdered sugar, and vanilla extract on medium-high speed for 3 to 6 minutes until lightened in color and glossy with a meringue-like texture.
05 -
Gradually add the cooled chocolate mixture to the sugar and egg mixture, stirring gently until uniform in color.
06 -
Sift together flour, cornstarch, and salt. Gently fold into wet batter using a spatula without overmixing. Fold in chocolate chunks and toasted nuts if using.
07 -
Pour batter evenly into prepared pan and smooth surface. Bake for approximately 25 minutes or until edges are set and toothpick inserted in the center comes out with moist crumbs. Begin checking at 23 minutes.
08 -
Allow brownies to cool completely in pan. For cleaner slices, chill before cutting and wipe knife between cuts. Serve plain or topped with ice cream.