01 -
Preheat oven to 175°C (350°F). Lightly grease an 8×12-inch baking pan with cooking oil spray. Line with parchment paper (or baking paper) and set aside.
02 -
In a medium-sized bowl, combine the melted butter, vegetable oil, white sugar, and brown sugar. Whisk well until thoroughly combined. Add the eggs and vanilla extract, then beat until the mixture becomes lighter in color (about one minute).
03 -
Sift the flour, cocoa powder, and salt into the wet ingredients. Gently fold the dry ingredients into the wet ingredients until JUST combined. Do NOT over beat, as this will affect the texture of your brownies, making them more cake-like rather than fudgy.
04 -
Fold in about ¾ of the chocolate pieces, distributing them evenly throughout the batter.
05 -
Pour the batter into the prepared baking pan, smoothing the top to make it even. Sprinkle the remaining chocolate pieces over the top of the batter.
06 -
Bake for 25-30 minutes for fudgier, slightly under-done brownies, or until the center no longer jiggles and is just set to the touch. For well-set and firmer brownies, bake for 35-40 minutes. Note that brownies will continue to bake and set in the hot pan after removing from the oven. If testing with a toothpick, it should come out dirty for fudge-textured brownies.
07 -
After 15-20 minutes, carefully remove the brownies from the pan using the parchment paper overhang. Allow them to cool to room temperature before slicing into 16 pieces. The brownies will continue to set as they cool.