Cook pasta according to package directions.
Meanwhile, in a small skillet, salute green pepper and onion in 1 teaspoon butter until tender; set aside.
In a large bowl, combine crab, shrimp, egg, mozzarella cheese, mayonnaise, 2 tablespoons milk, 1 teaspoon seafood seasoning, black pepper and green bell pepper.
Pre-heat oven to 350°F.
Drain and rinse pasta; stuff each shell with 1 rounded tablespoon of seafood mixture.
Place in a greased 13 x 9-inch baking dish.
In a small saucepan, melt remaining butter over medium heat.
Whisk in flour and coarsely ground pepper; gradually whisk in remaining milk.
Bring to a boil; cook and stir 2 minutes or until thickened.
Stir in Parmesan cheese.
Pour over stuffed shells.
Sprinkle with remaining seafood seasoning.
Bake, uncovered, 30 – 35 minutes or until bubbly.
