Preheat the oven to 350 degrees F and grease your 9x13 casserole dish.
Begin by making both the brownie and cookie dough separately. To make the cookie dough, combine the all of the dry ingredients, other than the chocolate chips, in a bowl.
Slowly pour in the wet ingredients and continue to mix until a dough begins to form. The dough will be soft and moldable.
Fold in the chocolate chips and continue to mix until they are well combined. It can be a lightly thick, so using your hands may be necessary.
Using a separate bowl, begin making the brownie batter. Combine all of the dry ingredients into a bowl.
Slowly pour in the wet ingredients and continue to mix until a dough begins to form. The dough will be soft and moldable - it will not be liquid in texture like non vegan brownie batter
Add in the chocolate chips and continue to mix until they are well combined. You may need to use your hands again to mix it completely.
Begin layering your slutty brownie bars. First, mold your cookie dough into the bottom of the casserole dish. Do this by placing the cookie dough in the casserole dish and pressing it down with your hand until an even layer forms.
Next, layer your oreos. Place an even layer of oreos to cover the entire cookie dough layer. You may need to break some oreos in half to make them properly fit.
Next, layer on your brownie batter. You will do this the same way you layered the cookie dough, pressing it down to form a layer.
Place in the oven and bake for 20-22 minutes or until you can remove a toothpick cleanly from the center. The slutty brownies will look somewhat raw, as they are a gooey cookie bar. They are fully cooked.
Allow to cool for at least 10 minutes before serving. For best cutting results, run a clean knife under warm to hot water in between each cut.