Line bottom and sides of an 8-inch square pan with aluminum foil, allowing 2 to 3 inches to extend over sides. Generously grease foil. Melt 1 cup butter in a 3-qt. saucepan over low heat. Stir in brown sugar, sweetened condensed milk, and corn syrup until smooth. Bring to a boil. Cook over medium heat, stirring constantly, until a candy thermometer registers 235° (about 20 minutes). Remove from heat. Add orange zest; stir 1 minute or until mixture is smooth and no longer bubbling. Quickly pour into prepared pan. Let stand 2 hours. Lift caramels from pan, using foil sides as handles. Cut into 2- x 1-inch pieces with a buttered knife. Store at room temperature up to 1 week. To package for gifting, wrap each piece in a taffy wrapper.
PACKAGE IN: Medium Glassine Bag (20 cents; thinkgarnish.com)