Roll out the puff pastry on a lightly-floured surface until about 1/4 inch thick. With a knife or a cutter, cut out rounds or ovals about 5-6 inches across.
Beat the egg with 1 tsp. water. Brush the tops of the pastry with the egg wash. Place the pastry on an ungreased cookie sheet. Bake in the preheated 400-degree oven for 15-20 minutes, until golden brown.
After cooling, split the pastries as you would a biscuit. Cut out the doughy parts of the inside of the pastry, and set the pastry aside.
In a skillet over medium heat, heat the butter until it bubbles and saute the shallots until clear. Add the oysters and shrimp and saute about three minutes, until the oysters begin to curl at the edges and the shrimp turn pink. Add the crawfish and crabmeat and stir in to heat through--about one minute.
Measure the Cognac into a glass and then pour it into the pan. Carefully touch a flame to it and allow the flames to die out. Add the fish stock and bring to a boil. Remove the seafood with a slotted spoon and set aside.
Whisk in the whipping cream slowly and bring to a slow simmer. Return the seafood to the pan, along with the green onions. Stir lightly until the seafood are incorporated into the sauce. Add the Tabasco and salt and pepper to taste.
Place a bottom half of each puff pastry on each serving plate. Divide the sauced seafood among the plates and top with the other half of the pastry.
