Use a meat mallet or a or a rolling pin to crush the shell of the cooked lobster and set shell aside. Remove lobster meat and place in the fridge with the crab meat for later.
Heat a deep skillet over medium high heat and add olive oil. Once hot add the lobster shell, salt, and pepper. Cook for 2 minutes, then add diced celery and diced red onion. Cook for 2 minutes, then lower heat to a simmer and add vegetable broth. Cook for 10 minutes. Pour broth into a bowl with a pour spout and discard the shells
In the same skillet, add butter and rice wine vinegar. Once melted, add minced garlic and shallot and cook for 1 minute. Add to the broth.
Cut the lobster tail right where the tail starts to fan out (about 2” from the end) and add that small section of the tail to the broth. Refrigerate the rest of the lobster tails for later use.
Pour broth into the slow cooker. Add canned tomatoes, Cherry tomatoes, old Bay seasoning, red pepper flakes, garlic powder, and onion powder. Cover and cook on low for 5 hours.
During the final 30 minutes of cooking time, add the lobster tails to the slow cooker and cook until red.
Take the meat from the whole lobster and crab out of the fridge and chop. Remove all of the shelled lobster tails from the soup. Take the meat out of the shells and chop. (Discard shells)
Combine lobster and crab meat in a medium mixing bowl and season with remaining old bay seasoning.
Use an immersion blender to blend the soup mixture in the slow cooker. Stir in the heavy cream, chives, lobster, and crab meat.
Garnish with fresh chopped parsley, shaved Parmesan, and croutons.