Preheat oven to 185 degrees C and lightly grease a regular cake tin.
For the eclair crust:
In a medium saucepan, melt butter in water and bring to a boil. Remove from heat. Stir in flour. Mix in one egg at a time, mixing completely before adding another egg. Spread mixture into pan, covering the bottom and sides evenly. Mixture will be very wet. (If the sides of your pan are too greased you won't be able to get the mixture to stay up the sides so make sure to just lightly grease. No big deal but I like the crust to go up the sides a bit.)
Bake for 30-40 minutes or until golden brown. You may want to check it occasionally-you don't want to overcook the crust, it will ruin the cake! Remove from oven and let cool (don't touch or push bubbles down).
For the filling:
Whip cream cheese in a medium bowl. Slowly add pudding to cream cheese, mixing until there are no lumps. Let cool in fridge. When the crust is completely cooled, pour filling in.
Make whipped cream to taste. I like mine sweet and add caster sugar to taste and vanilla.
Once it is cool and set, top with whipped topping.
Homemade chocolate sauce:
Stir cocoa and sugar together well. In a saucepan combine milk, butter, salt and vanilla. Stir in dry mix. Heat, stirring until it reaches a boil and is thick. You want it to coat the back of a spoon. If you want it to be thicker, for a crepe filling for example, boil it a little longer. It will still be thin once you are done with this step. Don't worry once you let it cool down a bit it will thicken. It will thicken a lot when chilled. Makes around 1 cup of sauce.