Preheat and prep. Heat your oven to 375°F (190°C). Lightly grease a small baking dish (about 1 quart) with butter or olive oil spray.
Sauté the aromatics. In a skillet, melt the butter over medium heat.
Add the minced shallot and a pinch of salt. Cook until softened and fragrant, about 2–3 minutes. Stir in the garlic and cook 30 seconds more.
Cook the shrimp. Add the chopped shrimp to the skillet.
Season with a little salt and black pepper. Cook, stirring, until opaque and just cooked through, about 2–3 minutes. Remove from heat and let it cool slightly.
Mix the creamy base. In a large bowl, combine cream cheese, sour cream, and Greek yogurt.
Beat or stir until smooth. Mix in lemon juice, lemon zest, Old Bay, smoked paprika, cayenne (if using), and half of the parsley.
Fold in the seafood and cheese. Gently fold in the crab meat (saving any large beautiful lumps to place on top), the cooked shrimp mixture, Parmesan, and 1/2 cup of the mozzarella. Taste and adjust seasoning with salt and pepper.
Assemble and top. Spread the mixture evenly into the prepared baking dish.
Sprinkle the remaining 1/2 cup mozzarella on top. If you saved a few crab lumps, nestle them on the surface for a nice presentation.
Bake until bubbly. Bake 15–20 minutes, or until the dip is hot and bubbling around the edges. For a lightly browned top, switch the oven to broil for 1–2 minutes, watching closely.
Finish and serve. Let the dip rest 5 minutes so it sets slightly.
Garnish with the remaining parsley and a twist of black pepper. Serve warm with toasted baguette, crackers, or crisp veggies.