Steps:

• Place lobsters in the freezer to render them insensible (30 minutes), then kill humanely. Meanwhile, bring a very large saucepan of salted water to the boil. Boil lobsters until half-cooked (4 minutes). Drain, then using a sharp knife and kitchen scissors, split lobsters in half. Remove meat from tails and legs (leave head and tail shell intact), coarsely chop tail meat and transfer to a bowl. Set shells and meat aside separately until required.
• Meanwhile, preheat oven to 220C. For mornay sauce, heat butter in a saucepan over medium-high heat until foaming (2-3 minutes), add flour and stir continuously until flour begins to turn sand-coloured (2-3 minutes). Gradually add milk, stirring well between each addition, until incorporated and sauce is smooth, then stir in cheese, season well to taste and stir in thyme (see note).
• Arrange lobster shells on a crumpled piece of foil in a roasting tray (this helps to keep them upright). Combine half the mornay sauce with the lobster meat and stir to combine, then spoon mixture into shells, spoon extra sauce over to cover well, then roast until mornay turns golden and bubbly (20-30 minutes). Season to taste and serve hot with lemon wedges and a leaf salad.

Steps:

• Arrange a rack in the middle of the oven and heat the oven to 350°F.
• Melt 4 tablespoons unsalted butter in a medium saucepan over medium heat. Add 1/4 cup all-purpose flour and cook, stirring, until very lightly toasted, about 2 minutes. While whisking, slowly pour in 1 (8-ounce) bottle clam juice, then 3 cups whole milk. Season with 1 1/2 teaspoons kosher salt and 1/4 teaspoon black pepper. Bring to a boil over medium-high heat, stirring frequently. Reduce the heat to medium and simmer until thickened, 8 to 10 minutes more. Taste and season with more kosher salt and black pepper as needed.
• Meanwhile, cook 1 pound dried lasagna noodles in a large pot of salted boiling water according to package directions until al dente. Drain, rinse under cool water until cool, and drain well again. Arrange the noodles in an even layer on a large baking sheet, coating them with olive oil and overlapping them slightly if needed.
• Pick the leaves from 1/2 bunch fresh parsley and finely chop until you have 1/4 cup for the sauce and 1 tablespoon more for garnish. Juice 1/2 medium lemon until you have 1 tablespoon juice. Finely chop 4 garlic cloves.
• Melt 4 tablespoons unsalted butter in a large skillet over medium heat. Add the garlic and cook, stirring, until golden brown, about 3 minutes. Add 1/2 cup dry white wine and boil until the wine is almost evaporated, about 3 minutes. Add 1 pound raw tiny shrimp and cook, stirring occasionally, until the shrimp are pink and just cooked through, about 4 minutes.
• Remove the skillet from the heat. Add the 1/4 cup parsley, the lemon juice, and 1/4 teaspoon of the kosher salt, and stir to combine. Taste and season with more kosher salt as needed.
• Place 3 cups ricotta cheese, 3/4 cup finely grated Parmesan cheese, the remaining 1 teaspoon kosher salt, and 1/4 teaspoon black pepper in a medium bowl and stir to combine. Taste and season with more kosher salt and black pepper as needed.
• Spread 1/2 cup of the cream sauce in the bottom of a 9x13-inch inch baking dish. Arrange 1/3 of the noodles over the cream sauce, overlapping them as needed. Spread half the ricotta mixture over the noodles. Evenly arrange half the shrimp mixture, half the lobster, and half the crab over the ricotta. Sprinkle with 1 cup of the mozzarella.
• Dollop and spread 1 cup of the cream sauce over the cheese. Repeat layering half the remaining noodles, the remaining ricotta mixture, and the remaining shrimp mixture, lobster, and crab. Sprinkle with 1 cup of the mozzarella cheese. Dollop and spread 1 cup of the cream sauce over the cheese. Top with the remaining lasagna noodles, spread with the remaining cream sauce, and sprinkle with the remaining 2 cups mozzarella.
• Coat a large sheet of aluminum foil with cooking spray. Loosely cover the baking dish the foil spray-side down. Bake for 30 minutes. Uncover and bake until golden-brown and bubbly, 20 to 25 minutes more. Let cool for at least 15 minutes before slicing. Garnish with the reserved parsley before serving.