In large saucepan or Dutch oven, cook spaghetti to desired doneness as directed on package. Drain; return to saucepan.
Meanwhile, heat oven to 350°F. Grease 10- or 9-inch deep-dish pie pan or quiche dish.
To cooked spaghetti, add 2 tablespoons margarine, Parmesan cheese and eggs; stir gently. Spread over bottom and up sides of greased pie pan.
In large bowl, combine broccoli, flour, Alfredo sauce and tuna; mix well. Spoon into spaghetti crust. In small bowl, combine bread crumbs and 1 teaspoon melted margarine; mix well. Sprinkle over tuna mixture.
Bake at 350°F. for 40 to 45 minutes or until spaghetti is light golden brown. Let stand 5 minutes before serving.