Place flour into a bowl and rub in butter until mixture resembles crumbs.  Mix to a dough with 2 tablespoons of cold water.  Form into 2 balls and then pat into 2 ovals on a lined baking tray.  Set aside (these 2 ovals will be the bases of your pastries).

Place 1 cup of water and second measure of butter into a saucepan and bring to the boil - remove from the heat and immediately mix in 1 cup flour and mix well over a gentle heat until mixture comes away from the sides of the saucepan.  Allow mixture to cool .

Preheat oven to 180 C.  Mix the eggs into the flour/butter mixture, one at a time, beating well after each.
Add essence and mix well.  Divide the mixture in half and pile on top of the bases.  Bake for 1 hour or until puffed, firm and coloured - keeping an eye on pastry darkening too quickly.
Ice with combined icing sugar and cream while still warm and sprinkle with walnuts.