Combine first 5 ingredients in a medium bowl. Com-bine buttermilk and egg substitute; add to dry ingredients, stirring just until dry ingredients are moistened.
Pour batter into a 9-inch square pan coated with cooking spray.
Bake at 350 for 30 minutes.
Remove from oven, and let cornbread cool completely on a wire rack.
Cut cornbread into 8 rectangles.
Place rectangles on a baking sheet; brush with one-half of melted margarine. Broil 3 inches from heat (with electric oven door partially opened) 1 to 2 minutes or until lightly browned. Turn cornbread; brush with remaining melted margarine. Broil 3 inches from heat (with electric oven door partially opened) 1 to 2 additional minutes or until lightly browned.