Preheat the oven to 350°F (175°C) and line an 8x8 inch baking pan with parchment paper. Set it aside.

In a microwave-safe bowl, melt the butter, vegetable oil, granulated sugar, and brown sugar together in 30-second intervals. Mix after each interval. Once fully melted, microwave for another 1 minute and stir vigorously to allow the sugar to dissolve.

Using a hand mixer or stand mixer, whisk in the eggs one at a time. Then add the vanilla extract.

Add the flour, cocoa powder, and salt to the wet mixture and fold just until combined.

Pour half of the brownie batter into the prepared baking pan and spread it evenly.

Place the Oreos in the center of the batter. Then, top with the remaining brownie batter and spread it to cover the Oreos.

Crush the extra 5 Oreos and sprinkle them on top of the brownie batter.

Bake in the preheated oven for 30 minutes.

Let the brownies cool completely on a wire rack before slicing them into squares.