In a large skillet, melt 2 tablespoons of butter and 1 tablespoon of olive oil over medium heat. Once sizzling, add 1 finely chopped onion and sauté for about 3-4 minutes until translucent. Next, add 2 cloves of minced garlic and cook for an additional 30 seconds until fragrant.

Stir in 1 pound of peeled and deveined shrimp and 1 cup of crab meat into the skillet. Sprinkle with salt, pepper, and 1 teaspoon of paprika. Cook for approximately 2-3 minutes, until the shrimp are pink and opaque.

In a separate saucepan, melt 4 tablespoons of butter over medium-low heat. Whisk in ¼ cup of flour to form a roux, stirring continuously for about 1-2 minutes until lightly golden. Gradually add in 2 cups of warm milk, stirring until smooth, then whisk in 1 cup of heavy cream. Allow to simmer for 5 minutes until thickened.

Sprinkle in 1 cup of grated Parmesan cheese and 1 cup of shredded mozzarella cheese into the sauce, stirring until melted and well combined. Adjust seasoning with a pinch of nutmeg, salt, and pepper.

Preheat your oven to 375°F (190°C). In a 9x13 baking dish, ladle a layer of the cheese sauce, followed by a layer of lasagna noodles, seafood mixture, and more sauce. Repeat layers, finishing with a sauce layer on top.

Cover the lasagna with aluminum foil and bake for 25 minutes covered, then remove the foil and bake for an additional 15 minutes until golden and bubbly.

Once baked, take the lasagna out and allow it to rest for about 10 minutes. This helps the layers set for clean serving.

Before serving, sprinkle fresh parsley on top for color and freshness, optionally garnishing with a few shrimp.