Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish with cooking spray or butter.

Make the sauce by melting the butter in a medium saucepan over medium heat. Stir in the flour and whisk until smooth. Cook for 1 minute, then slowly pour in the heavy cream and clam juice, whisking constantly to avoid lumps.

Cook the sauce for 5-7 minutes, stirring often, until it thickens. Stir in garlic powder, onion powder, nutmeg (if using), italian seasoning, 1/2 cup parmesan, and season with salt and pepper. Remove from heat and set aside.

Heat olive oil in a skillet over medium heat. Sauté the onion for 3-4 minutes until soft. Add the shrimp and cook for 2-3 minutes, just until they turn pink. Remove from heat and gently fold in the crab meat, and chopped parsley.

Spread a thin layer of sauce over the bottom of the baking dish. Add enough lasagna noodles to cover the bottom, overlapping slightly if necessary.

Spread a third of the seafood mixture over the noodles, followed by a third of the sauce. Sprinkle on a 1/3 of the shredded mozzarella.

Repeat the layers two more times, finishing with a final layer of noodles, the remaining sauce, and topping with the remaining shredded cheese.

Cover the dish tightly with aluminum foil, being careful not to touch the cheese. Bake for 30 minutes, then remove the foil and bake uncovered for another 15-20 minutes, or until the top is golden and bubbly. Let it rest for 10 minutes before serving. Garnish with parsley. Enjoy!