Preheat oven to 425*F (220 °C) Slightly overlap patty shells on a lightly floured board. Roll out to an l8 x 9" rectangle. Brush with beaten egg. Sprinkle half of pastry with 2 tablespoons Parmesan cheese; fold other half over to make a square. Roll out to a 16" x 12" rectangle. Brush with beaten egg and sprinkle with remaining Parmesan cheese Combine sesame seeds, parsley flakes, celery salt and thyme; sprinkle evenly over cheese. With a sharp knife or pastry cutter, cut pastry lengthwise into 1-inch wide strips; then cut crosswise to make 1 inch squares. Place squares on ungreased baking sheet and heat at 375*F (190*C) for 5 minutes. Makes about 120 appetisers.