LINE 8 x 4- or 9 x 5-inch loaf pan with foil.
MICROWAVE broken baking bars and sweetened condensed milk in medium, uncovered, microwave-safe bowl on HIGH (100%) power for 1 minute; STIR. If pieces retain some of their original shape, microwave at additional 10- to 15-second intervals, stirring just until smooth.
STIR in nuts and vanilla extract. Spread into prepared loaf pan. Refrigerate for 2 hours or until firm. Lift from pan; remove foil. Cut into 24 pieces.
FOR ROCKY ROAD FUDGE:
PREPARE fudge as above. Stir 3/4 cup miniature marshmallows into melted chocolate mixture with nuts and vanilla extract.
NOTE: Recipes can easily doubled. For the sweetened condensed milk, use 1 can (14 oz.). Fudge can be spread into foil-lined 8- or 9-inch baking pan.