1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Mix Base Ingredients: In a large mixing bowl, combine cream cheese, sour cream, and mayonnaise until smooth.
3. Add Seafood and Seasonings: Stir in the chopped shrimp, lump crab meat, spinach, Parmesan cheese, green onions, garlic, Old Bay seasoning, red pepper flakes, salt, and pepper.
4. Transfer to Baking Dish: Transfer the mixture to a baking dish and smooth the top.

5. Add Topping: Sprinkle shredded mozzarella cheese over the top.
6. Bake: Bake in the preheated oven for 20-25 minutes, or until bubbly and golden on top.
7. Serve: Serve hot with crackers, sliced baguettes, or tortilla chips.

Additional Details:
– Prep Time: 10 minutes
– Cooking Time: 25 minutes
– Total Time: 35 minutes
– Calories: 250 kcal per serving
– Servings: 6 servings