Start by gently cracking the cooked lobster shell with a meat mallet or rolling pin, then set the shell aside. Carefully extract the lobster meat and chill it along with the crab meat.

In a deep skillet over medium-high heat, pour in the olive oil. Once hot, add the lobster shell, sea salt, and black pepper. Sauté for about 2 minutes, then toss in the chopped celery and diced red onion, cooking for an additional 2 minutes. Lower the heat and pour in the vegetable stock, allowing it to simmer for 10 minutes. Transfer the broth to a bowl with a spout and discard the shells.

In the same skillet, melt the butter with rice wine vinegar. After it melts, add the minced garlic and shallot, cooking for 1 minute before adding this mixture to the broth.

For the lobster tails, cut them about 2 inches from the fan end and add that small piece to the broth. Reserve the rest of the tails in the fridge.

Pour the broth into your slow cooker. Mix in the canned tomatoes, cherry tomatoes, Old Bay seasoning, red pepper flakes, garlic powder, and onion powder. Cover and let it cook on low for 5 hours.

In the last 30 minutes of cooking, add the lobster tails to the slow cooker and cook until they turn red.

Retrieve the lobster and crab meat from the fridge, chopping it up. Remove the lobster tails from the soup, take out the meat from the shells, and discard the shells.

In a bowl, combine the chopped lobster and crab meat with the leftover Old Bay seasoning.

Use an immersion blender to blend the soup in the slow cooker until smooth. Stir in the heavy cream, chopped chives, and the lobster and crab mixture.

Serve warm, garnished with fresh parsley, shaved Parmesan, and crunchy croutons.