Instructions

• Preheat the oven to 350°F. Grease an 8x8-inch baking pan or line it with parchment paper, leaving an overhang for easy removal.
• In a small bowl, stir together the flour, cocoa powder, baking soda, and salt until evenly combined.
• In a large mixing bowl, beat the butter, brown sugar, and granulated sugar with an electric mixer (or in a stand mixer) until well creamed and slightly fluffy, about 3 minutes.
• Add the egg and vanilla to the creamed mixture and beat until fully incorporated.
• Add the dry ingredients to the wet ingredients and mix just until combined—do not overmix.
• Fold in the chopped Oreos and the white chocolate chips until distributed evenly through the dough.
• Transfer the dough to the prepared 8x8 pan and press it into an even layer using a spatula or your hands (wet or lightly greased hands help).
• Bake for 18–25 minutes, until the edges are set and a toothpick inserted into the center comes out with a few moist crumbs (cookie pieces or melted chips may stick).
• Let the bars cool in the pan on a wire rack. Use the parchment overhang (if used) to lift the slab out, then cut into bars once cooled.