In small bowl, combine eggs, onions and basil; blend well. Spray medium skillet with nonstick cooking spray. Place Canadian bacon in sprayed skillet. Cook over medium heat about 1 minute on each side or until hot; remove from skillet.
Add egg mixture to skillet. Cook until eggs are firm but still moist, stirring frequently. Spread 4 bagel halves with mustard. Top each with 1 lettuce leaf, 1 slice Canadian bacon, 1 slice tomato, 1/4 of the egg mixture and bagel half.