1. Preheat oven to 350 degrees Fahrenheit. Grease a 9×13-inch glass Pyrex or disposable pan.
2. In a large bowl, combine cocoa powder and boiling water.
3. In another bowl, mix flour, baking powder, baking soda, and salt until combined.
4. Add oil, vanilla sugar, and sugar to the cocoa mixture and mix.
5. Pour flour mixture into the cocoa mixture and mix until combined. Add in the vinegar and mix.
6. Immediately pour batter into pan.
7. Bake for 25–30 minutes.
8. While cake is baking, pour milk into a bowl and add in instant chocolate pudding. Mix and set aside until cake is ready.
9. Place whipped topping in a bowl and beat for three to four minutes or until almost stiff. Add in instant vanilla pudding and beat until stiff. Add in crushed Oreos and mix gently with a spoon.
10. While cake is still warm, use the handle of a wooden spoon to poke many holes in the top of the cake. Spread pudding over warm cake with a spatula, gently spreading pudding into each hole.
11. Place cake in the fridge to cool.
12. Remove from fridge and spread the Oreo whipped cream on the cake. Drizzle chocolate syrup (you can run a knife through for a pretty design). Sprinkle crushed Oreos on top.