In a mixing bowl, combine the instant vanilla pudding mix and milk. Whisk together until the mixture thickens.
In another bowl, beat the softened cream cheese and powdered sugar together until smooth. Gently fold in the Cool Whip until fully combined.
Once the pudding mixture has thickened, fold it into the cream cheese mixture until smooth and well combined.
In the prepared baking dish, lay down a layer of graham crackers at the bottom.
Spread half of the vanilla filling over the graham crackers.
Add another layer of graham crackers on top of the filling.
Spread the remaining filling over the second layer of graham crackers, followed by a final layer of graham crackers.
In a separate bowl, mix the chocolate syrup with the chocolate frosting until smooth. Spread this mixture evenly over the top layer of graham crackers.
Cover the dish and refrigerate for at least 4 hours (or overnight) to allow the flavors to meld and the cake to set.
Slice into squares and serve chilled.