Line an 8-by-8-by-2-inch or 9-by-9-by-2-inch baking pan with foil, extending foil over the edges of pan. Butter foil; set aside.

Stir baking pieces and sweetened condensed milk in a large heavy saucepan over low heat just until pieces are melted and mixture is smooth. Remove from heat. Stir in lime peel and lime juice. Stir in the 1 cup chopped macadamia nuts. Spread mixture evenly into the prepared pan. If desired, sprinkle the coarsely chopped macadamia nuts on top.

Cover and chill for two hours or until firm. Lift the fudge from pan using edges of foil. Peel off foil and use a knife to cut fudge into pieces. Store in an airtight container at room temperature for up to one week or in the freezer for up to 2 months. Makes 2 1/2 pounds or 64 servings.