Preheat oven to 400 degrees. Spray 9x13 glass baking dish with nonstick cooking spray and set aside.
In a medium pot, bring butter and water to a boil. Remove from heat and whisk in flour, salt and sugar until a dough forms. Cool 10 minutes.
Stir in eggs, 1 at a time, incorporating each time to make a smooth mixture that will seem half way between a dough and a batter.
Once all eggs are incorporated, pour into prepared baking dish and spread evenly across the bottom and up the sides 3/4 inch or so. Bake for 25 minutes or until puffed and lightly golden. Cool completely.
In a large bowl, whisk vanilla pudding mix with egg nog 2 minutes to thicken. Stir in cream cheese and mix until smooth. A stand mixer or hand held mixer is best for this! Spread over the bottom of the baked shell.
For the topping, whip heavy whipping cream with vanilla and powdered sugar until stiff peaks form. Spread over filling. Refrigerate up to 3 days {covered completely with plastic wrap}.To serve, cut into squares and drizzle with chocolate syrup.