In a small saucepan over low heat, melt the unsalted butter until bubbly, then add chocolate chips and stir until smooth. Set aside to cool slightly.

In a large bowl, whisk together the white and brown sugars until fully combined, ensuring no lumps remain.

Add the eggs, vanilla extract, and salt to the sugar mixture. Beat until smooth and fluffy, then fold in the cooled chocolate mixture.

Sift in the flour and cocoa powder gradually, folding until the batter is smooth, being careful not to overmix.

Fold in crushed Oreos until evenly distributed throughout the batter.

Preheat the oven to 350°F (175°C). Line an 8x8 baking dish with parchment paper and pour in the brownie batter.

Bake for approximately 30 minutes. Check for doneness with a toothpick, which should come out with a few moist crumbs.

Remove from the oven and cool in the pan for at least 20 minutes before slicing and serving.