Bring a large pot with water on the stove to boil on medium-high heat. The pot should be large enough to fit the potatoes and corn.
Rinse the potatoes and then add them, alongside the corn, to the pot, season with salt, and leave to boil for 12-15 minutes. To check if the potatoes are ready, pierce them with a fork. They should be fork-tender but not falling apart.
To check if the corn is ready, notice the change in color from a lighter to a more intense yellow, and the kernels become fuller and plumper.
When both are cooked, remove them from the water and set them aside.
Slice andouille sausage into ½-1″ pieces diagonally. Add sliced sausage in a skillet or saucepan over medium-high heat, add sliced sausage, and cook until slightly browned, 3-5 minutes. Transfer sausage to a plate and set aside.
Add butter to the saucepan. When the butter melts, add the diced red onion and garlic. Saute for about 5 minutes until the onion is translucent.
Next, add chicken broth, Old Bay seasoning, Creole seasoning, paprika, and cayenne pepper. Stir well. Reduce the heat to low and allow to cook for about 5-7 minutes.
Season with salt and pepper to taste, and add fresh lemon juice and parsley. Mix to fully combine. Cook for an additional minute, then turn off the heat and set aside.
Preheat the oven to 400℉/205℃. Place the bags in a large bowl to stabilize while filling.
Add the thawed snow crab legs, deveined shrimp, sliced andouille sausage, hard-boiled eggs, potatoes, and corn to the oven bag (Divide ingredients into the bags equally). Drizzle the butter sauce throughout and tie the oven bags to seal them.
Toss the contents around in the bags to ensure they are fully coated with the sauce.
Place the bags on a sheet pan or in a baking dish and place it in the oven.
Bake for 20-25 minutes, flipping the bags halfway during the cooking process.
Take the bag out of the oven and allow it to rest for about 5 minutes before opening (hot steam will escape when opened).
Garnish with parsley, arrange lemon wedges around the spread and your seafood is ready to be served.