Bring 2 2/3 cups water to a boil; add grits, and cook, stirring often, 5 minutes or until thickened. Remove from heat. Add margarine and next 4 ingredients, stirring until blended. Spoon mixture into a 2-quart baking dish coated with cooking spray.
Bake at 350° for 40 minutes or until lightly browned.
NOTE: Casserole may be chilled up to 8 hours. Let stand at room temperature 30 minutes; bake as directed.