Preheat your oven to 400°F.
In a large mixing bowl, combine the cream cheese, mayonnaise, sour cream, mozzarella, parmesan, lemon juice, Worcestershire sauce, and 2 teaspoons of Cajun seasoning with an electric hand mixer or wooden spoon. Set aside.
Melt the butter in a 10-inch cast-iron skillet over medium-high heat. Add the bell pepper, onion, and green onion and cook for 2-3 minutes until softened. Add the garlic, shrimp, and 1 tablespoon of Cajun seasoning, and cook for 3 to 5 minutes until the shrimp are pink and opaque. Do not overcook the shrimp! Set the 3 whole shrimp aside.
Pour the shrimp mixture into the bowl with the cheese mixture and mix until combined. Pour the dip back into the cast-iron skillet and bake for 20 to 25 minutes until golden and bubbly around the edges.
Garnish the dip with the reserved 3 whole shrimp and chopped green onions. Serve with chips or veggies for dipping.