Preheat oven to 400 F. For the pastry box: Using a sharp knife, make corner slits in the top right corner and on the bottom left corner, leaving a 1-inch border. Pull the right corner to the left corner and vice versa. Place on a baking sheet and bake for 10 to 15 minutes, or until golden brown. Now make the filling. In a saute pan heat olive oil. When the pan is smoking hot, saute the shallots and garlic for about 1 to 2 minutes. Then add the fish stock, white wine, and heavy cream. Season with salt and pepper. Bring liquid up to a boil, then reduce to a simmer. Add the potatoes, oysters, clam, mussels. Cover pan and cook for about 4 to 5 minutes or until the liquid had reduced by half, the potatoes are tender, and the mussels have opened. Then remove from heat. Remove the boxes from the oven and divide the sauce into fourths and spoon into the boxes. Garnish with parsley and grated cheese.