Step 1: Preheat your grill to medium-high heat (about 400°F / 200°C) or your oven to 400°F (200°C).
Step 2: In a small bowl, whisk together the melted butter, Old Bay seasoning, garlic powder, onion powder, paprika, and cayenne pepper. Season with salt and black pepper.
Step 3: In a large bowl, combine the shrimp, smoked sausage, corn, and baby potatoes. Pour the seasoned butter mixture over the ingredients and toss gently to ensure everything is evenly coated.
Step 4: Tear four large (about 18x12-inch) pieces of heavy-duty aluminum foil. For extra strength, you can double up each piece of foil. Divide the seasoned mixture evenly among the four foil pieces.
Step 5: Bring the long sides of the foil together over the ingredients and fold down tightly to seal. Then, fold up the shorter ends to create a securely sealed packet. Ensure there are no gaps for steam to escape.
Step 6: If grilling, place the packets directly on the preheated grill grates. Cook for 15-20 minutes, flipping once halfway through, until shrimp are pink and opaque, and potatoes are tender. If baking, place the packets on a baking sheet and bake for 20-25 minutes, or until cooked through.
Step 7: Carefully open the foil packets (watch out for steam!) and serve immediately with fresh lemon wedges and an optional sprinkle of fresh parsley.