Preheat the oven to 375°F/190℃.
Line a baking dish with foil or parchment paper and spray with a nonstick cooking spray.
Place crabmeat in a large bowl and season it with creole seasoning. Alternatively, you can use just salt and pepper to season it.
Add the egg and mayonnaise and mix lightly, then cover and refrigerate the mixture while preparing the other ingredients.
Add butter to a skillet over medium heat. Add the onions, minced garlic, green onions, celery, red pepper, parsley, and creole seasoning as soon as it melts. Sauté for about 3-5 minutes and then transfer to a bowl. Rest until cool.
While the sauteed veggies cool, crush the crackers until they have a fine crumb texture.
Once the sauteed veggies are cool, start adding the cream cheese, crushed crackers, sauteed veggies, and parmesan into the crabmeat mixture. Gently fold in all the ingredients until it’s thoroughly mixed.
Test the mixture and add salt and pepper as needed.
Place shrimp on a cutting board and cut a slit in the underside of the shrimp about ¾ deep, stopping at the tail so they can lie tail-side up.
Season the shrimp lightly with creole seasoning and salt if you desire.
Use a spoon to stuff each shrimp with 1-2 tablespoons of crabmeat.
Carefully place the shrimp in your prepared baking dish, stuffed side up, and then spray them with cooking spray.
Bake until golden brown for about 20 minutes.
Remove from the oven and serve right away.