Directions

• Stuffing:
• Melt the butter in a large skillet over medium heat and add the onion and green pepper; cook until softened. Add chopped shrimp if using and toss to cook slightly. Remove from the heat and set aside to cool slightly. Toast the bread slices, sprinkle each piece with a good spray of water to wet them and set aside in a bowl. Let sit for about 2 minutes. Pick through the crabmeat to check for stray shell; set aside.
• Squeeze out the bread and break it up. Add the egg to the bread and mix. Add the salt, pepper, Cajun seasoning, Old Bay, parsley and sautéed onion and bell pepper; carefully turn until well mixed. Add the crab and gently mix. 
• Flounder:
• Preheat oven to 350°F.  Line a large baking pan with foil and spray it generously with non-stick cooking spray. 
• Cut a slit lengthwise head to tail, down the dark side of the flounder and make pockets on both sides of the slit by using a sharp fillet knife to carefully cut along the back bones of the fish. Cut all the way to the upper and lower fins, without cutting through. Sprinkle the flounder with salt and pepper and fill the cavities of each flounder with the stuffing mix, placing each onto the prepared pan. Squeeze lemon juice over the top, and drizzle with about half of the melted butter.
• Bake uncovered at 350°F for about 30 minutes, or until fish flakes easily, basting with the remaining butter about halfway through. To brown more on top, place the tray under the broiler with the oven door ajar, very briefly, just long enough to brown the top of the stuffing. Serve with wedges of lemon on the side and a generous side salad.
• Topping:
• Season shrimp and scallops with Cajun seasoning or Blackening seasoning
• SautéIf you can only get your hands on flounder filets, you can still do this! Just cut each half filet into half width-wise, rather than length-wise. Lay out each half in buttered baking dish, top with stuffing, and top with the other half of fish, slightly mashing. Bake as above, checking at 20 minutes. May also prepare as roulades by placing stuffing on widest part of half filet and rolling fish up around stuffing. Secure with toothpick and place into baking sheet. Bake approximately 5 minutes, turn and bake another 3 to 5 minutes, depending on size. shrimp and scallops in butter or olive oil until done
• Pour sauce over fish and toppings and serve