Fresh Crabmeat and Lobster Lasagna

Name: Fresh Crabmeat and Lobster Lasagna
Ingredients: 6 tablespoons butter; 6 tablespoons all-purpose flour; 4 cups milk; Salt; Freshly ground white pepper; Pinch ground nutmeg; 1/2 pound fresh spinach, cleaned, stemmed and cut into thin strips; 8 ounces grated Parmigiano-Reggiano; 2 cups ricotta cheese; 1 egg; 2 teaspoons chopped garlic; 8 ounces grated mozzarella cheese; 3/4 pound lump crabmeat, picked over for cartilage; 1 1/2 pound lobster, cooked, meat removed and diced; 1/2 pound fresh pasta sheets; Truffle oil, for serving, optional