Grease a 9x13" oven dish and preheat your oven to 350° F
In a medium size saucepan over low heat, melt the chocolate with the butter, stirring occasionally until smooth. Cool for 10 minutes. Transfer this mixture to a large bowl and mix in the sugar, the eggs, the vinegar and the vanilla extract.
Mix in the flour and pour half of the batter into the prepared pan.
Arrange 24 Oreo cookies evenly on top.
Pour the rest of the batter. Separate the 2 parts of the remaining Oreo cookies and cut each into 2. Arrange them on the top of the batter.
Bake for 25-28 minutes or until a cake tester inserted into center of pan comes out with moist crumbs attached. Do not over bake.
Allow to cool to room temperature, or overnight, before cutting and serving.