Preheat oven to 375 degrees F. Thaw shrimp, if frozen. Peel and devein shrimp. Rinse shrimp; pat dry with paper towels. Set aside.
Cook noodles according to package directions; drain. Rinse with cold water; drain again.
for shrimp sauce:
Meanwhile, in a large saucepan, heat 1 tablespoon of the butter over medium heat. Add mushrooms; cook and stir about 3 minutes or until tender and browned. Stir in tomatoes, onion powder, dried oregano, salt, and pepper. Bring to boiling; reduce heat. Simmer sauce, uncovered, about 10 minutes or until all of the liquid is evaporated. Remove from heat. Stir in shrimp. Cover and set aside.
For cheese sauce:
In a medium saucepan, heat the remaining 3 tablespoons butter over medium heat. Stir in flour. Gradually stir in milk. Cook and stir until thickened and bubbly. Add Swiss cheese and wine; stir until cheese is melted.
To assemble, in an ungreased 2-quart rectangular baking dish, layer half of the shrimp sauce, four of the cooked noodles, and half of the cheese sauce. Repeat layering shrimp sauce, noodles, and cheese sauce. Sprinkle with the 1/4 cup Romano cheese. Place baking dish in a shallow baking pan (for drip catching).
Bake, uncovered, about 30 minutes or until edges are bubbly and top is lightly browned. Let stand for 20 minutes before serving. If desired, garnish with the fresh oregano leaves and serve with additional Romano cheese. Makes 8 servings.