In a saucepan, melt the butter, then whisk in the cocoa powder and sugar.
Remove from heat.
Whisk in the salt, vanilla, and eggs.
Stir in flour. Set aside.
Next, mix the cookie dough.
Beat together the butter and sugars.
Mix in vanilla and egg.
Stir in the dry ingredients, then mix in the chocolate chips.
Preheat the oven to 350°. Line a 9 x 9-inch pan with non-stick foil.
Press the cookie dough into the bottom of the pan, trying to make it level.
Lay Oreos over the cookie dough, cutting some in half if necessary.
Pour on the brownie batter and spread to cover the Oreos using an offset spatula.
Bake for 35-40 minutes.
Cool for a few hours before cutting.
