Cook sausage in a nonstick skillet over medium-high heat until browned, stirring until it crumbles.
Combine egg substitute and next 6 ingredients in a medium bowl; stir well with a wire whisk. Stir in sausage, green onions, and bread cubes. Pour mixture into an 11- x 7- x 1 1/2-inch baking dish coated with cooking spray; cover and chill at least 8 hours.
Bake, uncovered, at 350° for 45 minutes or until set and lightly browned. Cut into squares, and serve with sliced tomato.