Preheat the oven to 350 degrees, and line a large baking sheet (with sides) with non-stick foil.
Place Oreos side by side on the baking sheet (for my pan, I needed 44 Oreos). Set aside.
Crush remaining Oreos into smaller pieces. Reserve 1/3 of the Oreos for the topping. Use the remaining 2/3 Oreo pieces to fill in the gaps between the Oreos on the baking tray (see video for more detail). Set aside.
In a medium sized saucepan, bring butter and brown sugar to a boil, whisking constantly. Once the mixture has reached a boil, reduce the heat to med-low, whisking for 3 minutes.
Remove from the heat, and pour the mixture over the Oreos. With a rubber spatula or spoon, spread the mixture out into an even layer.
Bake the toffee for 6-7 minutes, or until the liquid is bubbling.
Immediately sprinkle chocolate chips over the top, and allow to stand for 1-2 minutes (this allows the chocolate to begin melting.)
With a spatula, spoon, or knife, spread the chocolate in an even layer over the toffee and sprinkle with the remaining 1/3 cup of Oreos crumbs.
Refrigerate for at least 1 hour before cutting or breaking into pieces.
Enjoy!
(Leftovers can be stored at room temperature or in the fridge)