Prepare the boil: In a large stockpot or Dutch oven (at least 10 quarts), combine the water and beer (if using) over medium-high heat. Bring the liquid to a boil. Then, add the Creole Cajun seasoning, Old Bay seasoning, and hot sauce to taste. Toss in the sliced onion and lemon wedges. Stir well to combine all the ingredients. Let the mixture boil for 15 minutes.
Add the andouille & potatoes: Carefully add the andouille sausage rounds and baby potatoes into the pot, stirring to combine them with the boil. Let the andouille and potatoes cook for 15-20 minutes, or until the potatoes are nearly fork-tender.
Add the seafood & corn: Gently add the snow crab clusters, shrimp, and corn on the cob into the pot, ensuring everything is fully submerged in the boil. Stir carefully to mix the ingredients. Continue boiling for another 5-7 minutes, or until the shrimp turns pink. Meanwhile, prepare the garlic butter sauce.
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 (to taste). Stir and simmer the sauce for 5-7 minutes, until the butter melts and the ingredients blend well. Remove from heat.
Assemble the Cajun seafood boil with sauce: Line a large baking sheet with foil or parchment paper (or newspaper, if you prefer). Use a spider strainer to remove the seafood boil contents from the pot and transfer them to the prepared baking sheet. Add the hard-boiled eggs (if using), and discard the onion and lemon bits. If you’d like a thinner garlic butter sauce, you can add some of the seafood boil broth to reach the desired consistency. Now, the fun part! Pour the garlic butter sauce over the seafood and vegetables, then use your hands (with disposable gloves if preferred) to toss everything together, ensuring every piece is smothered in the sauce.
Serve the seafood boil: Serve the Cajun seafood boil as-is, allowing everyone to grab what they want directly from the baking sheet (enjoy the chaos and mess!), or divide the boil into individual plates for a cleaner presentation. Serve immediately with extra lemon wedges, if desired. Be sure to enjoy every drop of the garlic butter sauce. Enjoy!