Preheat the oven to 350º F. Line a 8x8 or 9x9 inch pan with aluminum foil or parchment paper. Spray lightly with non-stick cooking spray. 

In a mixing bowl, combine the properly measured flour, salt and cocoa powder. Stir together with a spoon until mixed. Set aside. 

In a small saucepan over low heat, combine the chopped unsweetened chocolate and cubed butter. Stir occasionally until it’s fully melted, about 5 minutes.

Meanwhile, in a larger mixing bowl, beat the granulated sugar and eggs plus additional egg yolk with an electric mixer for 1 minute, until the mixture is pale yellow and doubled in volume. 

Once the chocolate is melted, pour it into the egg mixture. Then add the vegetable oil and vanilla extract. Stir with a spatula to combine. 

Spoon the flour mixture into the wet ingredients, add the crushed oreos for the batter and mix with a spatula just until combined. Do not continue to mix the batter once you can no longer see flour. 

Pour the brownie batter into the prepared pan and press the additional rough chopped oreos on top, pushing them into the batter. Bake for 35-40 minutes (glass pan) 27-32 minutes (metal pan) or until a toothpick inserted in the center comes out clean. Allow the brownies to cool, then slice.