1. Preheat oven to 350 degrees F. Melt butter in large saucepan on medium heat. Add flour; stir with wire whisk until well blended. Gradually add milk, mixing well after each addition. Bring to boil on medium heat, stirring constantly. Reduce heat to low; simmer 3 to 5 min. or until thickened, stirring constantly. Remove from heat. Stir in Parmesan cheese; set aside. Combine spinach, cottage cheese, 2/3 cup of the mozzarella cheese and the nutmeg.
2. Spread 1/4 of the Parmesan cheese sauce onto bottom of 13x9-inch baking pan. Cover with 3 of the lasagna noodles and layers of 1/2 each of the shrimp, crabmeat and spinach mixture; top with 1/4 of the Parmesan cheese sauce. Repeat layers, starting with the noodles. Top with remaining 3 lasagna noodles, remaining Parmesan cheese sauce and the remaining 1/3 cup mozzarella cheese. Cover with foil.
3. Bake 25 min. Uncover; bake an additional 20 min. or until lasagna is heated through and top is lightly browned. Let stand 10 min. before cutting into 12 pieces to serve.

Yield: 12 servings