Start by preparing the boil. In a very large stockpot or Dutch oven, add the water and beer if you’re using it. Bring it to a strong boil over medium-high heat. Add the Creole Cajun seasoning, Old Bay seasoning, and a few dashes of hot sauce. Stir well. Add the sliced onion and lemon wedges. Let this boil for about 15 minutes so the flavors build.
Next, carefully add the sliced andouille sausage and baby potatoes. Stir gently. Let them cook for 15 to 20 minutes, until the potatoes are just fork-tender. They should be soft but not falling apart.
Now add the snow crab legs, shrimp, and corn. Make sure everything is under the liquid. Stir gently so it all cooks evenly. Boil for another 5 to 7 minutes, just until the shrimp turn pink and opaque. Do not overcook.
While that cooks, make the garlic butter sauce. In a small saucepan over medium heat, combine the butter, garlic, lemon juice, Old Bay seasoning, parsley, Creole Cajun seasoning, smoked paprika, and hot sauce. Stir often as the butter melts. Let it simmer gently for about 5 to 7 minutes until everything is combined. Remove from heat.
To assemble, line a large baking sheet with foil or parchment paper. Using a strainer, carefully remove the seafood, sausage, potatoes, and corn from the pot and place them on the tray. Add the hard boiled eggs if using. Discard the onion and lemon pieces.
If you want a thinner sauce, stir in a little of the cooking broth into the butter sauce. Pour the warm garlic butter over everything. Toss gently to coat well.
Serve right away with extra lemon wedges. Let everyone dig in and enjoy.