Prep the oven: Preheat to 375°F (190°C). Lightly grease a small baking dish (about 1–1.5 quarts) or an oven-safe skillet.
Cook the shrimp: Pat shrimp dry.
Warm olive oil in a skillet over medium heat. Add garlic and cook 30 seconds until fragrant. Stir in shrimp, Old Bay, salt, and pepper.
Cook 2–3 minutes until just pink. Remove from heat and toss with lemon zest and juice. Let cool slightly.
Make the creamy base: In a mixing bowl, beat cream cheese until smooth.
Stir in sour cream, mayonnaise, hot sauce, Worcestershire, and cayenne. Season with a pinch of salt and pepper.
Add cheeses and veggies: Fold in 1 cup mozzarella, 1/4 cup Parmesan, green onions, and red bell pepper.
Combine with shrimp: Fold the warm shrimp and any juices from the skillet into the cheese mixture. Taste and adjust seasoning—add more hot sauce, lemon, or salt as needed.
Assemble: Spread the mixture into the prepared dish.
Top with remaining 1/2 cup mozzarella and 1/4 cup Parmesan.
Bake: Bake 18–22 minutes, until hot and bubbling around the edges. For a deeper golden top, broil 1–2 minutes at the end.
Finish and serve: Let sit 5 minutes to set. Sprinkle with chopped green onions and parsley.
Serve warm with your favorite dippers.