Butter square 9"x9"x2" pan.
Heat margarine in a 3 quart saucepan until melted then add marshmallows, cooking over low heat, stirring constantly until melted and mixture is smooth. Remove from heat.
Stir in cereal and nuts until well covered. Press evenly in pan using back of a buttered spoon.
Heat chocolate chips and shortening in a 1 quart saucepan over low heat, stirring constantly until melted and mixture is smooth.
Spread over cereal mixture. Refrigerate until firm. Cut into 1 1/2" squares. Makes 36 squares. Enjoy!