Preheat the oven to 350°F. Line a 9x13-inch baking dish with parchment paper with some hanging over the edges of the pan (this will help with removing the brownies later).
Press the cookie dough into the bottom of the baking dish into an even layer. Note: this will be easier to do if you don’t try to press it in as soon as you remove the dough from the refrigerator. Let it sit out for a few minutes.
In a single layer, place the Oreo cookies evenly on top of the cookie dough and gently press it into the cookie dough. Set aside.
In a large bowl, prepare the brownie batter according to package directions with the eggs, water and vegetable oil).
Pour the prepared brownie batter evenly on top of the Oreo cookies and gently spread it out to make sure it’s covering all the cookies.
Next, gently tap the pan on the counter a couple of times to help the brownie batter get in between the Oreo cookies.
Bake for 30 minutes, then loosely cover the baking dish with aluminum foil and bake for an additional 15-20 minutes (until a toothpick inserted comes out clean).
Let cool completely.
Using the parchment paper, lift the brookie bars out of the baking dish. Cut into 15 squares.
At this point, chop up 10 additional Oreo cookies to use as the topping (note, this is optional)
Melt the chocolate wafers per the directions on the back of the package; you will need about 1 cup of melted chocolate. Drizzle the melted chocolate onto the top of each brookie bar.
Then immediately sprinkle the top with the crushed Oreo cookies.
Allow the brookie bars to sit for about 20-30 minutes until the melted chocolate has set, then serve.
Notes
Please refer to my FAQ’s (Frequently Asked Questions) and ingredient list above for other substitutions or for the answers to the most common questions.
Keep at room temperature for up to 5 days in a sealed container. These are best eaten at room temperature.
Wrap individual bars in plastic wrap and then foil and place in a freezer-safe container or bag—place in the freezer, where they will keep for about 3 months. Thaw on the counter or in the fridge overnight. Again, best eaten at room temp.