Preheat the oven: Set to 375°F (190°C). Lightly grease a 1- to 1.5-quart baking dish or an 8-inch skillet.
Season and sauté the shrimp: In a large skillet over medium heat, melt the butter. Add garlic and cook 30 seconds until fragrant.
Stir in the chopped shrimp, 2 teaspoons Cajun seasoning, smoked paprika, cayenne (if using), salt, and pepper. Cook 2–3 minutes until shrimp are just pink and opaque. Remove from heat and let cool slightly.
Make the creamy base: In a mixing bowl, combine cream cheese, sour cream, and mayonnaise.
Beat until smooth. Mix in lemon juice and Worcestershire.
Fold in flavor add-ins: Stir in red bell pepper, green onions, half the parsley, 1 cup Monterey Jack, and all the Parmesan. Taste and adjust salt, pepper, and Cajun seasoning as needed.
Add the shrimp: Gently fold the sautéed shrimp and any skillet juices into the creamy mixture.
Don’t overmix; you want small, tender pieces throughout.
Assemble: Transfer to the prepared baking dish. Top with the remaining 1/2 cup Monterey Jack.
Bake: Bake 18–22 minutes, until hot and bubbling around the edges and the cheese on top is melted and lightly golden.
Finish and serve: Sprinkle with the remaining parsley, a pinch of Cajun seasoning, and a little lemon zest if you like. Serve warm with toasted bread, crackers, or veggies.