Cook pasta according to package directions, omitting salt and fat.
Melt margarine in a heavy saucepan over low heat; add flour, stirring until smooth. Cook, stirring constantly, 1 minute. Gradually add milk; cook over medium heat, stirring constantly, until thickened and bubbly. Add cheese and salt, stirring until cheese melts. Gradually stir about one-fourth cheese mixture into egg substitute. Add egg substitute mixture to remaining cheese mixture, stirring constantly.
Combine cheese sauce and pasta; pour into a 2-quart baking dish coated with cooking spray. Sprinkle with paprika. Bake at 350° for 25 to 30 minutes or until thoroughly heated.