Cook macaroni according to package directions, omitting salt and fat; drain well, and set aside.
Combine flour and 2 tablespoons milk, stirring until smooth. Combine flour mixture, remaining 1/4 cup plus 2 tablespoons milk, and margarine in a small saucepan, stirring well. Cook over medium heat, stirring constantly, until mixture is thickened and bubbly. Remove from heat; add cheese and next 3 ingredients, stirring until cheese melts. Add egg substitute, stirring constantly.
Combine cooked macaroni and cheese sauce, stirring well. Pour mixture into a 1 1/2-cup casserole coated with cooking spray. Combine breadcrumbs and paprika; sprinkle in rows on top of macaroni mixture. Bake, uncovered, at 350° for 20 to 25 minutes or until bubbly. If desired, garnish with tomato and parsley.