Melt 2 tablespoons of unsalted butter over medium heat in a large skillet. Add minced garlic and chopped shallots, sauté until fragrant for about 2 minutes. Add shrimp and scallops, cooking until opaque (3-4 minutes). Gently fold in crab meat and remove from heat.

Melt 4 tablespoons of unsalted butter over low heat in a saucepan. Stir in ¼ cup of flour, whisk for 2 minutes to form a roux. Gradually add 3 cups of warmed milk, whisking consistently for 5-7 minutes until the sauce thickens. Season with salt, pepper, and a pinch of nutmeg, then remove from heat.

In a bowl, combine 1 cup of ricotta cheese, ½ cup of grated Parmesan cheese, lemon zest, and parsley. Mix until creamy, adding salt and pepper to taste.

Preheat oven to 375°F (190°C). In a buttered baking dish, layer ½ cup of béchamel sauce, followed by lasagna noodles, a third of the ricotta mixture, half of the seafood, and shredded mozzarella. Repeat layers, finishing with béchamel and mozzarella on top.

Cover with aluminum foil and bake for 30 minutes. Remove foil and bake for an additional 10-15 minutes until the top is golden. Allow to cool for 10 minutes before serving.