Begin by boiling water for the noodles. In a large skillet saute onion and green pepper in butter until tender. Add tomatoes, mushrooms, olives and oregano and simmer as you brown ground beef in a smaller skillet, add to vegetable mixture.
When noodles are cooked, place half in a greased 13" x 9" x 2" baking dish. Top with half of the vegetable mixture. Sprinkle with 1 cup cheddar cheese. Repeat layers.
Mix soup with water until smooth, pour over casserole. Sprinkle with parmesan cheese.
Baked uncovered at 350 degrees for 45 minutes or until heated through.