Coat an 8- x 8-inch pan with cooking spray.
Stir together sugar, evaporated milk and margarine. Bring to a boil in a sauce pan, reduce heat to medium-low and cook 3 minutes, stirring constantly.
Stir in chocolate and marshmallows. Remove from heat and stir until smooth.
Pour into pan and refrigerate until firm, about 2 hours. Cut into 36 squares and serve. (Leave fudge in refrigerator or freezer for a firmer consistency.)
Nutrition Information per serving:
91 Cal., 3 g. fat, 0 g. fiber