Preheat oven to 350°.
Peel and de-vein shrimp if needed.
Cook the macaroni according to package directions. Drain well.
Place drained macaroni in a large mixing bowl.
Add the sour cream, stir together well, until all noodles are coated.
Add the crab meat, stir well.
Finely chop the green onion. Set Aside.
Grate the white cheddar cheese. Set aside.
Grate the mozzarella cheese. Set aside.
Melt the butter in a medium sauce pan, or skillet.
Add the shrimp. Turn and stir shrimp until lightly done.
Remove shrimp from pan. Chop slightly when cooled. Add to the macaroni mixture.
Add the finely chopped onions to the sauce pan, sauté until tender.
Sprinkle flour over onions and mix well. Let cook and brown for about one minute.
Slowly add the milk, stirring constantly until mixture begins to thicken.
Gradually add the grated Cheddar Cheese, stirring constantly until cheese melts.
Pour cheese mixture over the macaroni and seafood mixture. Stir well to combine.
Add salt and pepper to taste.
Place the mixture in a well buttered baking dish.
Sprinkle top with grated mozzarella cheese.
Sprinkle bread crumbs on top of the mozzarella cheese.
Sprinkle lightly with Paprika, to add color.
Bake at 350° for 20-25 minutes, or until lightly browned on top.
Serve warm and Enjoy!
Use your favorite combinations of seafood to make this dish. If you like your mac and cheese a little creamier, add another half cup of milk to the recipe when adding the evaporated milk.