1 pkg. (16 oz.) elbow macaroni, cooked and drained
1/2 cup grated Parmesan cheese
1-1/2 cups fresh breadcrumbs
2 tbsp. fresh chopped parsley
Preheat oven to 350°F. Coat a 3-quart baking dish with cooking spray.
Cook Shrimp Scampi as directed on package. Remove shrimp tails and discard.
Meanwhile, melt 6 tablespoons butter in a large saucepan over medium heat. Whisk in flour until blended. Gradually whisk in milk; bring to a simmer and cook 3 minutes. Stir in the Gruyere until melted. Stir in the cheddar, Swiss cheese, salt and pepper until blended.
Remove from heat. Stir in Shrimp Scampi, shrimp cooking liquids and macaroni until combined. Spoon into prepared baking dish. Top with Parmesan and breadcrumbs. Drizzle with the remaining 3 tablespoons melted butter.
Cover with foil and bake 45 minutes or until heated through. Uncover, sprinkle on parsley and bake 15 minutes more or until golden.