Preheat the oven to 400°F (200°C) and lightly grease a 1-quart baking dish so the dip doesn’t stick.
In a large bowl, mix the softened cream cheese, mayonnaise, and sour cream until smooth and creamy. If the cream cheese feels too firm, let it sit out for a few minutes first.
Stir in the shredded Parmesan, cheddar cheese, lemon juice, hot sauce, salt, and black pepper until everything is well combined and evenly blended.
Gently fold in the lump crab meat, keeping the pieces as intact as possible for better texture.
Transfer the mixture into the prepared baking dish and spread it evenly across the surface.
Sprinkle the remaining ¼ cup Parmesan cheese over the top to create a lightly golden finish.
Bake for 25–35 minutes, until the dip is hot, bubbly around the edges, and slightly golden on top. If it browns too quickly, loosely cover with foil.
Let it rest for a couple of minutes after removing from the oven, then top with sliced green onions and serve warm.