Preheat your oven to 350°F (175°C). Grease your 9x13 inch baking pan or line it with parchment paper for easier removal later.
In a large mixing bowl, beat the unsalted butter, granulated sugar, and light brown sugar together until creamy and smooth, about 2-3 minutes. Add in the eggs and vanilla extract, mixing until fully combined.
In another bowl, whisk together the all-purpose flour, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the milk chocolate chips.
Prepare your brownie mix according to the package instructions or your favorite homemade recipe.
Spread half of the cookie dough evenly into the bottom of the prepared baking pan. Layer the Double Stuffed Oreos on top, pressing them down gently. Pour the brownie batter over the Oreos, spreading it out evenly. Drop spoonfuls of the remaining cookie dough on top.
Bake for 30-35 minutes, or until the top is golden brown and a toothpick comes out with a few moist crumbs.
Allow to cool in the pan for 10-15 minutes. Drizzle the hot fudge topping over the top while still warm.
Let the bars cool completely in the pan before slicing into squares.
